{"id":34132,"date":"2026-10-20T17:38:05","date_gmt":"2026-10-20T10:38:05","guid":{"rendered":"https:\/\/etest.edu.vn\/?p=34132"},"modified":"2026-10-20T17:38:05","modified_gmt":"2026-10-20T10:38:05","slug":"chord-of-a-circle-la-gi-cong-thuc-tinh-chat-day-cung-va-bai-tap-minh-hoa","status":"publish","type":"post","link":"https:\/\/etest.edu.vn\/en\/chord-of-a-circle-la-gi-cong-thuc-tinh-chat-day-cung-va-bai-tap-minh-hoa\/","title":{"rendered":"Chord of a Circle l\u00e0 g\u00ec? C\u00f4ng th\u1ee9c, t\u00ednh ch\u1ea5t d\u00e2y cung v\u00e0 b\u00e0i t\u1eadp minh h\u1ecda"},"content":{"rendered":"<h1><b>Chord of a Circle l\u00e0 g\u00ec? C\u00f4ng th\u1ee9c, t\u00ednh ch\u1ea5t d\u00e2y cung v\u00e0 b\u00e0i t\u1eadp minh h\u1ecda<\/b><\/h1>\n<p><span style=\"font-weight: 400;\">Trong h\u00ecnh h\u1ecdc, Chord of a Circle (d\u00e2y cung c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n) l\u00e0 m\u1ed9t kh\u00e1i ni\u1ec7m quan tr\u1ecdng, th\u01b0\u1eddng xu\u1ea5t hi\u1ec7n trong c\u00e1c b\u00e0i to\u00e1n v\u1ec1 \u0111\u1ed9 d\u00e0i, kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung v\u00e0 quan h\u1ec7 gi\u1eefa c\u00e1c d\u00e2y cung. \u0110\u1ed1i v\u1edbi h\u1ecdc sinh \u0111ang \u00f4n luy\u1ec7n SAT Math, vi\u1ec7c hi\u1ec3u r\u00f5 kh\u00e1i ni\u1ec7m n\u00e0y gi\u00fap gi\u1ea3i quy\u1ebft nhi\u1ec1u d\u1ea1ng b\u00e0i h\u00ecnh h\u1ecdc, \u0111\u1eb7c bi\u1ec7t l\u00e0 nh\u1eefng c\u00e2u h\u1ecfi k\u1ebft h\u1ee3p \u0111\u1ecbnh l\u00fd Pythagoras, b\u00e1n k\u00ednh v\u00e0 g\u00f3c \u1edf t\u00e2m.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">B\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y s\u1ebd gi\u1ea3i th\u00edch Chord of a Circle l\u00e0 g\u00ec, t\u1ed5ng h\u1ee3p c\u00e1c c\u00f4ng th\u1ee9c v\u00e0 t\u00ednh ch\u1ea5t quan tr\u1ecdng, \u0111\u1ed3ng th\u1eddi cung c\u1ea5p v\u00ed d\u1ee5 c\u00f3 l\u1eddi gi\u1ea3i \u0111\u1ec3 b\u1ea1n d\u1ec5 d\u00e0ng \u00e1p d\u1ee5ng v\u00e0o b\u00e0i t\u1eadp.<\/span><\/p>\n<figure id=\"attachment_34144\" aria-describedby=\"caption-attachment-34144\" style=\"width: 711px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" class=\"wp-image-34144 size-medium\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18-711x400.jpg\" alt=\"\" width=\"711\" height=\"400\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18-711x400.jpg 711w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18-1400x788.jpg 1400w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18-768x432.jpg 768w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18-1536x864.jpg 1536w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18-18x10.jpg 18w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-1-18.jpg 1920w\" sizes=\"(max-width: 711px) 100vw, 711px\" \/><figcaption id=\"caption-attachment-34144\" class=\"wp-caption-text\">Chord of a Circle l\u00e0 g\u00ec? C\u00f4ng th\u1ee9c, t\u00ednh ch\u1ea5t d\u00e2y cung v\u00e0 b\u00e0i t\u1eadp minh h\u1ecda<\/figcaption><\/figure>\n<h2><b>1. Chord of a Circle l\u00e0 g\u00ec?<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">Chord of a Circle (d\u00e2y cung \u0111\u01b0\u1eddng tr\u00f2n) l\u00e0 \u0111o\u1ea1n th\u1eb3ng n\u1ed1i hai \u0111i\u1ec3m b\u1ea5t k\u1ef3 n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">V\u00ed d\u1ee5, \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 t\u00e2m <\/span><span style=\"font-weight: 400;\">O<\/span><span style=\"font-weight: 400;\">, hai \u0111i\u1ec3m <\/span><span style=\"font-weight: 400;\">A<\/span><span style=\"font-weight: 400;\"> and <\/span><span style=\"font-weight: 400;\">B<\/span><span style=\"font-weight: 400;\"> n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n. Khi n\u1ed1i <\/span><span style=\"font-weight: 400;\">A<\/span><span style=\"font-weight: 400;\"> with <\/span><span style=\"font-weight: 400;\">B<\/span><span style=\"font-weight: 400;\">, \u0111o\u1ea1n th\u1eb3ng <\/span><span style=\"font-weight: 400;\">AB<\/span><span style=\"font-weight: 400;\"> \u0111\u01b0\u1ee3c g\u1ecdi l\u00e0 d\u00e2y cung.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">K\u00fd hi\u1ec7u: D\u00e2y cung AB \u0111\u01b0\u1ee3c bi\u1ec3u di\u1ec5n b\u1eb1ng \u0111o\u1ea1n th\u1eb3ng <\/span><span style=\"font-weight: 400;\">AB<\/span><span style=\"font-weight: 400;\">.<\/span><\/p>\n<figure id=\"attachment_34145\" aria-describedby=\"caption-attachment-34145\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" class=\"wp-image-34145 size-medium\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-400x400.jpg\" alt=\"\" width=\"400\" height=\"400\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-400x400.jpg 400w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-800x800.jpg 800w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-280x280.jpg 280w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-768x768.jpg 768w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-12x12.jpg 12w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1-250x250.jpg 250w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-1-1.jpg 1080w\" sizes=\"(max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-34145\" class=\"wp-caption-text\">Chord of a Circle (d\u00e2y cung \u0111\u01b0\u1eddng tr\u00f2n) l\u00e0 \u0111o\u1ea1n th\u1eb3ng n\u1ed1i hai \u0111i\u1ec3m b\u1ea5t k\u1ef3 n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n.<\/figcaption><\/figure>\n<p><span style=\"font-weight: 400;\">M\u1ed9t s\u1ed1 \u0111i\u1ec3m c\u1ea7n ghi nh\u1edb:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Hai \u0111\u1ea7u m\u00fat c\u1ee7a d\u00e2y cung \u0111\u1ec1u n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">\u0110\u01b0\u1eddng k\u00ednh l\u00e0 d\u00e2y cung d\u00e0i nh\u1ea5t c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n v\u00ec n\u00f3 \u0111i qua t\u00e2m.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Kh\u00f4ng ph\u1ea3i m\u1ecdi d\u00e2y cung \u0111\u1ec1u \u0111i qua t\u00e2m.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">D\u00e2y cung chia ph\u1ea7n b\u00ean trong \u0111\u01b0\u1eddng tr\u00f2n th\u00e0nh hai mi\u1ec1n, m\u1ed7i mi\u1ec1n \u0111\u01b0\u1ee3c gi\u1edbi h\u1ea1n b\u1edfi d\u00e2y cung v\u00e0 m\u1ed9t cung tr\u00f2n t\u01b0\u01a1ng \u1ee9ng.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">Ph\u00e2n bi\u1ec7t d\u00e2y cung v\u00e0 \u0111\u01b0\u1eddng k\u00ednh: \u0110\u01b0\u1eddng k\u00ednh l\u00e0 tr\u01b0\u1eddng h\u1ee3p \u0111\u1eb7c bi\u1ec7t c\u1ee7a d\u00e2y cung \u0111i qua t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n. N\u1ebfu b\u00e1n k\u00ednh l\u00e0 <\/span><span style=\"font-weight: 400;\">r<\/span><span style=\"font-weight: 400;\">, \u0111\u01b0\u1eddng k\u00ednh c\u00f3 \u0111\u1ed9 d\u00e0i <\/span><span style=\"font-weight: 400;\">d=2r<\/span><span style=\"font-weight: 400;\">.<\/span><\/p>\n<h2><b>2. C\u00f4ng th\u1ee9c t\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung \u0111\u01b0\u1eddng tr\u00f2n<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">\u0110\u1ed9 d\u00e0i d\u00e2y cung c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng nhi\u1ec1u c\u00f4ng th\u1ee9c, t\u00f9y thu\u1ed9c v\u00e0o d\u1eef ki\u1ec7n \u0111\u1ec1 b\u00e0i cung c\u1ea5p.<\/span><\/p>\n<h3><b>2.1. C\u00f4ng th\u1ee9c d\u00e2y cung theo b\u00e1n k\u00ednh v\u00e0 kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">Gi\u1ea3 s\u1eed \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 b\u00e1n k\u00ednh <\/span><span style=\"font-weight: 400;\">r<\/span><span style=\"font-weight: 400;\">, d\u00e2y cung <\/span><span style=\"font-weight: 400;\">AB<\/span><span style=\"font-weight: 400;\"> c\u00f3 \u0111\u1ed9 d\u00e0i <\/span><span style=\"font-weight: 400;\">c<\/span><span style=\"font-weight: 400;\">, v\u00e0 kho\u1ea3ng c\u00e1ch vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m <\/span><span style=\"font-weight: 400;\">O<\/span><span style=\"font-weight: 400;\"> \u0111\u1ebfn d\u00e2y cung l\u00e0 <\/span><span style=\"font-weight: 400;\">h<\/span><span style=\"font-weight: 400;\">.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">G\u1ecdi <\/span><span style=\"font-weight: 400;\">M<\/span><span style=\"font-weight: 400;\"> l\u00e0 ch\u00e2n \u0111\u01b0\u1eddng vu\u00f4ng g\u00f3c t\u1eeb <\/span><span style=\"font-weight: 400;\">O<\/span><span style=\"font-weight: 400;\"> xu\u1ed1ng <\/span><span style=\"font-weight: 400;\">AB<\/span><span style=\"font-weight: 400;\">. Khi \u0111\u00f3, <\/span><span style=\"font-weight: 400;\">M<\/span><span style=\"font-weight: 400;\"> l\u00e0 trung \u0111i\u1ec3m c\u1ee7a d\u00e2y cung, n\u00ean:<\/span><\/p>\n<p><img decoding=\"async\" class=\"size-full wp-image-34133 aligncenter\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/screenshot_1792491731.png\" alt=\"\" width=\"162\" height=\"50\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/screenshot_1792491731.png 162w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/screenshot_1792491731-18x6.png 18w\" sizes=\"(max-width: 162px) 100vw, 162px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Theo \u0111\u1ecbnh l\u00fd Pythagoras trong tam gi\u00e1c vu\u00f4ng <\/span><span style=\"font-weight: 400;\">OMA<\/span><span style=\"font-weight: 400;\">:<\/span><\/p>\n<p><img decoding=\"async\" class=\"size-full wp-image-34135 aligncenter\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/2-2.png\" alt=\"\" width=\"160\" height=\"48\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/2-2.png 160w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/2-2-18x5.png 18w\" sizes=\"(max-width: 160px) 100vw, 160px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Suy ra c\u00f4ng th\u1ee9c t\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung:\u00a0<\/span><\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\"><img decoding=\"async\" class=\"size-full wp-image-34136 aligncenter\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1.png\" alt=\"\" width=\"131\" height=\"73\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1.png 131w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1-18x10.png 18w\" sizes=\"(max-width: 131px) 100vw, 131px\" \/><\/span><\/p>\n<p>&nbsp;<\/p>\n<p><span style=\"font-weight: 400;\">In there:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">c<\/span><span style=\"font-weight: 400;\">: \u0111\u1ed9 d\u00e0i d\u00e2y cung.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">r<\/span><span style=\"font-weight: 400;\">: b\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">h<\/span><span style=\"font-weight: 400;\">: kho\u1ea3ng c\u00e1ch vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung.<\/span><\/li>\n<\/ul>\n<figure id=\"attachment_34146\" aria-describedby=\"caption-attachment-34146\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" class=\"wp-image-34146 size-medium\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-400x400.jpg\" alt=\"\" width=\"400\" height=\"400\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-400x400.jpg 400w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-800x800.jpg 800w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-280x280.jpg 280w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-768x768.jpg 768w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-12x12.jpg 12w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4-250x250.jpg 250w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-4.jpg 1080w\" sizes=\"(max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-34146\" class=\"wp-caption-text\">C\u00f4ng th\u1ee9c d\u00e2y cung theo b\u00e1n k\u00ednh v\u00e0 kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m<\/figcaption><\/figure>\n<h3><b>2.2. C\u00f4ng th\u1ee9c d\u00e2y cung theo b\u00e1n k\u00ednh v\u00e0 g\u00f3c \u1edf t\u00e2m<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">N\u1ebfu bi\u1ebft b\u00e1n k\u00ednh <\/span><span style=\"font-weight: 400;\">r<\/span><span style=\"font-weight: 400;\"> v\u00e0 g\u00f3c \u1edf t\u00e2m <\/span><span style=\"font-weight: 400;\"> ch\u1eafn d\u00e2y cung, \u0111\u1ed9 d\u00e0i d\u00e2y cung \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng:<\/span><\/p>\n<p><img decoding=\"async\" class=\"size-full wp-image-34137 aligncenter\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1.png\" alt=\"\" width=\"174\" height=\"71\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1.png 174w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1-18x7.png 18w\" sizes=\"(max-width: 174px) 100vw, 174px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">C\u00f4ng th\u1ee9c n\u00e0y \u00e1p d\u1ee5ng khi <\/span><span style=\"font-weight: 400;\"> l\u00e0 g\u00f3c \u1edf t\u00e2m, v\u1edbi <\/span><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\">18<\/span><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\"> \u0111\u1ed1i v\u1edbi d\u00e2y cung nh\u1ecf ho\u1eb7c \u0111\u01b0\u1eddng k\u00ednh.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">N\u1ebfu g\u00f3c \u0111\u01b0\u1ee3c cho b\u1eb1ng radian, c\u00f4ng th\u1ee9c t\u01b0\u01a1ng \u1ee9ng l\u00e0: <\/span><span style=\"font-weight: 400;\"><img decoding=\"async\" class=\"alignnone size-full wp-image-34137\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1.png\" alt=\"\" width=\"174\" height=\"71\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1.png 174w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1-18x7.png 18w\" sizes=\"(max-width: 174px) 100vw, 174px\" \/><\/span><\/p>\n<p><span style=\"font-weight: 400;\">L\u01b0u \u00fd r\u1eb1ng khi s\u1eed d\u1ee5ng m\u00e1y t\u00ednh, c\u1ea7n ki\u1ec3m tra ch\u1ebf \u0111\u1ed9 g\u00f3c l\u00e0 \u0111\u1ed9 (degree) hay radian theo \u0111\u01a1n v\u1ecb c\u1ee7a \u0111\u1ec1 b\u00e0i.\u00a0<\/span><\/p>\n<h2><b>3. Nh\u1eefng t\u00ednh ch\u1ea5t quan tr\u1ecdng c\u1ee7a d\u00e2y cung \u0111\u01b0\u1eddng tr\u00f2n<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">N\u1eafm v\u1eefng c\u00e1c t\u00ednh ch\u1ea5t d\u01b0\u1edbi \u0111\u00e2y s\u1ebd gi\u00fap b\u1ea1n gi\u1ea3i b\u00e0i t\u1eadp nhanh h\u01a1n v\u00e0 h\u1ea1n ch\u1ebf nh\u1ea7m l\u1eabn.<\/span><\/p>\n<h3><b>3.1. \u0110\u01b0\u1eddng vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">\u0110\u01b0\u1eddng th\u1eb3ng \u0111i qua t\u00e2m v\u00e0 vu\u00f4ng g\u00f3c v\u1edbi m\u1ed9t d\u00e2y cung s\u1ebd chia d\u00e2y cung \u0111\u00f3 th\u00e0nh hai \u0111o\u1ea1n b\u1eb1ng nhau.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">N\u1ebfu <\/span><span style=\"font-weight: 400;\">OM vu\u00f4ng g\u00f3c <\/span><span style=\"font-weight: 400;\">AB<\/span><span style=\"font-weight: 400;\">, th\u00ec: <\/span><span style=\"font-weight: 400;\">AM=MB<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Ng\u01b0\u1ee3c l\u1ea1i, \u0111\u01b0\u1eddng th\u1eb3ng n\u1ed1i t\u00e2m v\u1edbi trung \u0111i\u1ec3m c\u1ee7a m\u1ed9t d\u00e2y cung (kh\u00f4ng ph\u1ea3i \u0111\u01b0\u1eddng k\u00ednh) s\u1ebd vu\u00f4ng g\u00f3c v\u1edbi d\u00e2y cung \u0111\u00f3.\u00a0<\/span><\/p>\n<h3><b>3.2. C\u00e1c d\u00e2y cung b\u1eb1ng nhau c\u00e1ch \u0111\u1ec1u t\u00e2m<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">Trong c\u00f9ng m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n ho\u1eb7c c\u00e1c \u0111\u01b0\u1eddng tr\u00f2n b\u1eb1ng nhau, hai d\u00e2y cung c\u00f3 \u0111\u1ed9 d\u00e0i b\u1eb1ng nhau th\u00ec c\u00e1ch \u0111\u1ec1u t\u00e2m.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">Ng\u01b0\u1ee3c l\u1ea1i, d\u00e2y cung c\u00e0ng g\u1ea7n t\u00e2m th\u00ec c\u00e0ng d\u00e0i. D\u00e2y cung xa t\u00e2m h\u01a1n s\u1ebd ng\u1eafn h\u01a1n, n\u1ebfu so s\u00e1nh trong c\u00f9ng m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n.<\/span><\/p>\n<h3><b>3.3. \u0110\u01b0\u1eddng k\u00ednh l\u00e0 d\u00e2y cung d\u00e0i nh\u1ea5t<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">\u0110\u01b0\u1eddng k\u00ednh \u0111i qua t\u00e2m v\u00e0 c\u00f3 \u0111\u1ed9 d\u00e0i g\u1ea5p \u0111\u00f4i b\u00e1n k\u00ednh:\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400;\">d=2r<\/span><\/p>\n<p><span style=\"font-weight: 400;\">V\u00ec v\u1eady, kh\u00f4ng c\u00f3 d\u00e2y cung n\u00e0o trong c\u00f9ng m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n d\u00e0i h\u01a1n \u0111\u01b0\u1eddng k\u00ednh.\u00a0<\/span><\/p>\n<h3><b>3.4. Quan h\u1ec7 gi\u1eefa g\u00f3c \u1edf t\u00e2m v\u00e0 d\u00e2y cung<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">Trong c\u00f9ng m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n, hai g\u00f3c \u1edf t\u00e2m b\u1eb1ng nhau ch\u1eafn hai d\u00e2y cung b\u1eb1ng nhau. Ng\u01b0\u1ee3c l\u1ea1i, hai d\u00e2y cung b\u1eb1ng nhau c\u0169ng ch\u1eafn hai g\u00f3c \u1edf t\u00e2m b\u1eb1ng nhau khi x\u00e9t c\u00e1c g\u00f3c \u1edf t\u00e2m nh\u1ecf t\u01b0\u01a1ng \u1ee9ng.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u0110\u00e2y l\u00e0 t\u00ednh ch\u1ea5t th\u01b0\u1eddng \u0111\u01b0\u1ee3c d\u00f9ng trong c\u00e1c b\u00e0i to\u00e1n ch\u1ee9ng minh h\u00ecnh h\u1ecdc v\u00e0 t\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung.<\/span><\/p>\n<h2><b>4. Ph\u00e2n bi\u1ec7t Chord, Radius v\u00e0 Diameter<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">Ba kh\u00e1i ni\u1ec7m n\u00e0y c\u00f3 li\u00ean h\u1ec7 m\u1eadt thi\u1ebft nh\u01b0ng kh\u00f4ng gi\u1ed1ng nhau.<\/span><\/p>\n<table>\n<tbody>\n<tr>\n<td><b>Concept<\/b><\/td>\n<td><b>Define<\/b><\/td>\n<td><b>\u0110\u1eb7c \u0111i\u1ec3m<\/b><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Chord (d\u00e2y cung)<\/span><\/td>\n<td><span style=\"font-weight: 400;\">\u0110o\u1ea1n th\u1eb3ng n\u1ed1i hai \u0111i\u1ec3m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n<\/span><\/td>\n<td><span style=\"font-weight: 400;\">C\u00f3 th\u1ec3 \u0111i qua t\u00e2m ho\u1eb7c kh\u00f4ng<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Radius (b\u00e1n k\u00ednh)<\/span><\/td>\n<td><span style=\"font-weight: 400;\">\u0110o\u1ea1n th\u1eb3ng n\u1ed1i t\u00e2m v\u1edbi m\u1ed9t \u0111i\u1ec3m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n<\/span><\/td>\n<td><span style=\"font-weight: 400;\">B\u1eb1ng m\u1ed9t n\u1eeda \u0111\u01b0\u1eddng k\u00ednh<\/span><\/td>\n<\/tr>\n<tr>\n<td><span style=\"font-weight: 400;\">Diameter (\u0111\u01b0\u1eddng k\u00ednh)<\/span><\/td>\n<td><span style=\"font-weight: 400;\">D\u00e2y cung \u0111i qua t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n<\/span><\/td>\n<td><span style=\"font-weight: 400;\">L\u00e0 d\u00e2y cung d\u00e0i nh\u1ea5t<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2><b>5. B\u00e0i t\u1eadp minh h\u1ecda v\u1ec1 Chord of a Circle<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">D\u01b0\u1edbi \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 b\u00e0i t\u1eadp gi\u00fap b\u1ea1n c\u1ee7ng c\u1ed1 ki\u1ebfn th\u1ee9c v\u00e0 luy\u1ec7n c\u00e1ch \u00e1p d\u1ee5ng c\u00f4ng th\u1ee9c.<\/span><\/p>\n<h3><b>B\u00e0i t\u1eadp 1: T\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">M\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 b\u00e1n k\u00ednh <\/span><span style=\"font-weight: 400;\">13<\/span><span style=\"font-weight: 400;\"> cm. Kho\u1ea3ng c\u00e1ch vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung l\u00e0 <\/span><span style=\"font-weight: 400;\">5<\/span><span style=\"font-weight: 400;\"> cm. T\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">L\u1eddi gi\u1ea3i:<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u00c1p d\u1ee5ng c\u00f4ng th\u1ee9c:<\/span><\/p>\n<p><img decoding=\"async\" class=\"size-full wp-image-34136 aligncenter\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1.png\" alt=\"\" width=\"131\" height=\"73\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1.png 131w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1-18x10.png 18w\" sizes=\"(max-width: 131px) 100vw, 131px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Thay s\u1ed1:<\/span><\/p>\n<p>&nbsp;<\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34138\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/5-1.png\" alt=\"\" width=\"180\" height=\"74\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/5-1.png 180w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/5-1-18x7.png 18w\" sizes=\"(max-width: 180px) 100vw, 180px\" \/><\/p>\n<p>&nbsp;<\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34139\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/6-1.png\" alt=\"\" width=\"289\" height=\"94\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/6-1.png 289w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/6-1-18x6.png 18w\" sizes=\"(max-width: 289px) 100vw, 289px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Answer: <\/span><span style=\"font-weight: 400;\">24<\/span><span style=\"font-weight: 400;\"> cm.<\/span><\/p>\n<h3><b>B\u00e0i t\u1eadp 2: T\u00ednh b\u00e1n k\u00ednh \u0111\u01b0\u1eddng tr\u00f2n<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">M\u1ed9t d\u00e2y cung d\u00e0i <\/span><span style=\"font-weight: 400;\">16<\/span><span style=\"font-weight: 400;\"> cm v\u00e0 c\u00e1ch t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n <\/span><span style=\"font-weight: 400;\">6<\/span><span style=\"font-weight: 400;\"> cm. T\u00ednh b\u00e1n k\u00ednh.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">L\u1eddi gi\u1ea3i:<\/span><\/p>\n<p><span style=\"font-weight: 400;\">N\u1eeda d\u00e2y cung c\u00f3 \u0111\u1ed9 d\u00e0i:<\/span><\/p>\n<p>&nbsp;<\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34140\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/7-1.png\" alt=\"\" width=\"165\" height=\"53\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/7-1.png 165w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/7-1-18x6.png 18w\" sizes=\"(max-width: 165px) 100vw, 165px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Theo \u0111\u1ecbnh l\u00fd Pythagoras:<\/span><\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34141\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/8-1.png\" alt=\"\" width=\"296\" height=\"156\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/8-1.png 296w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/8-1-18x9.png 18w\" sizes=\"(max-width: 296px) 100vw, 296px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">Answer: <\/span><span style=\"font-weight: 400;\">10<\/span><span style=\"font-weight: 400;\"> cm.<\/span><\/p>\n<h3><b>B\u00e0i t\u1eadp 3: T\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung theo g\u00f3c \u1edf t\u00e2m<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">M\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 b\u00e1n k\u00ednh <\/span><span style=\"font-weight: 400;\">12<\/span><span style=\"font-weight: 400;\"> cm, g\u00f3c \u1edf t\u00e2m ch\u1eafn d\u00e2y cung b\u1eb1ng <\/span><span style=\"font-weight: 400;\">9<\/span><span style=\"font-weight: 400;\">0<\/span><span style=\"font-weight: 400;\">. T\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">L\u1eddi gi\u1ea3i:<\/span><\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34142\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/9.png\" alt=\"\" width=\"188\" height=\"194\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/9.png 188w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/9-12x12.png 12w\" sizes=\"(max-width: 188px) 100vw, 188px\" \/><\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34143\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/10.png\" alt=\"\" width=\"571\" height=\"197\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/10.png 571w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/10-18x6.png 18w\" sizes=\"(max-width: 571px) 100vw, 571px\" \/><\/p>\n<h2><b>6. Chord of a Circle c\u00f3 quan tr\u1ecdng trong SAT Math kh\u00f4ng?<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">Chord of a Circle l\u00e0 m\u1ed9t ch\u1ee7 \u0111\u1ec1 h\u00ecnh h\u1ecdc h\u1eefu \u00edch khi \u00f4n luy\u1ec7n Digital SAT Math. C\u00e1c c\u00e2u h\u1ecfi li\u00ean quan c\u00f3 th\u1ec3 y\u00eau c\u1ea7u h\u1ecdc sinh t\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung, t\u00ecm b\u00e1n k\u00ednh, x\u00e1c \u0111\u1ecbnh kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung ho\u1eb7c k\u1ebft h\u1ee3p d\u00e2y cung v\u1edbi g\u00f3c \u1edf t\u00e2m v\u00e0 \u0111\u1ecbnh l\u00fd Pythagoras.<\/span><\/p>\n<p><span style=\"font-weight: 400;\">\u0110\u1ec3 l\u00e0m t\u1ed1t d\u1ea1ng b\u00e0i n\u00e0y, h\u1ecdc sinh n\u00ean:<\/span><\/p>\n<ul>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Ghi nh\u1edb m\u1ed1i quan h\u1ec7 gi\u1eefa b\u00e1n k\u00ednh, d\u00e2y cung v\u00e0 \u0111\u01b0\u1eddng vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Nh\u1eadn di\u1ec7n d\u1eef ki\u1ec7n \u0111\u1ec3 l\u1ef1a ch\u1ecdn c\u00f4ng th\u1ee9c ph\u00f9 h\u1ee3p.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">V\u1ebd h\u00ecnh v\u00e0 \u0111\u00e1nh d\u1ea5u c\u00e1c \u0111o\u1ea1n th\u1eb3ng b\u1eb1ng nhau tr\u01b0\u1edbc khi t\u00ednh to\u00e1n.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Ki\u1ec3m tra \u0111\u01a1n v\u1ecb \u0111o v\u00e0 ch\u1ebf \u0111\u1ed9 g\u00f3c tr\u00ean m\u00e1y t\u00ednh.<\/span><\/li>\n<li style=\"font-weight: 400;\" aria-level=\"1\"><span style=\"font-weight: 400;\">Luy\u1ec7n t\u1eadp c\u00e1c b\u00e0i to\u00e1n k\u1ebft h\u1ee3p nhi\u1ec1u t\u00ednh ch\u1ea5t h\u00ecnh h\u1ecdc thay v\u00ec ch\u1ec9 h\u1ecdc thu\u1ed9c c\u00f4ng th\u1ee9c.<\/span><\/li>\n<\/ul>\n<p><span style=\"font-weight: 400;\">M\u1ed9t l\u1ed7i ph\u1ed5 bi\u1ebfn l\u00e0 nh\u1ea7m kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung v\u1edbi b\u00e1n k\u00ednh, ho\u1eb7c qu\u00ean r\u1eb1ng \u0111\u01b0\u1eddng vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m s\u1ebd chia d\u00e2y cung th\u00e0nh hai \u0111o\u1ea1n b\u1eb1ng nhau.<\/span><\/p>\n<figure id=\"attachment_34147\" aria-describedby=\"caption-attachment-34147\" style=\"width: 400px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" class=\"wp-image-34147 size-medium\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-400x400.jpg\" alt=\"\" width=\"400\" height=\"400\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-400x400.jpg 400w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-800x800.jpg 800w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-280x280.jpg 280w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-768x768.jpg 768w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-12x12.jpg 12w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1-250x250.jpg 250w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/Untitled-Design-2-1.jpg 1080w\" sizes=\"(max-width: 400px) 100vw, 400px\" \/><figcaption id=\"caption-attachment-34147\" class=\"wp-caption-text\">Chord of a Circle c\u00f3 quan tr\u1ecdng trong SAT Math kh\u00f4ng?<\/figcaption><\/figure>\n<h2><b>Luy\u1ec7n SAT Math c\u00f9ng ETEST<\/b><\/h2>\n<p><span style=\"font-weight: 400;\">\u0110\u1ec3 chinh ph\u1ee5c c\u00e1c c\u00e2u h\u1ecfi h\u00ecnh h\u1ecdc trong <\/span><a href=\"https:\/\/etest.edu.vn\/en\/digital-sat\/\"><span style=\"font-weight: 400;\">Digital SAT<\/span><\/a><span style=\"font-weight: 400;\"> Math, h\u1ecdc sinh c\u1ea7n k\u1ebft h\u1ee3p ki\u1ebfn th\u1ee9c n\u1ec1n t\u1ea3ng v\u1edbi k\u1ef9 n\u0103ng ph\u00e2n t\u00edch \u0111\u1ec1 v\u00e0 l\u1ef1a ch\u1ecdn ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3i ph\u00f9 h\u1ee3p.<\/span><a href=\"https:\/\/etest.edu.vn\/en\/\"><span style=\"font-weight: 400;\"> ETEST<\/span><\/a><span style=\"font-weight: 400;\"> \u0111\u1ecbnh h\u01b0\u1edbng <\/span><a href=\"https:\/\/etest.edu.vn\/en\/khoa-hoc\/luyen-thi-sat\/\"><span style=\"font-weight: 400;\">ch\u01b0\u01a1ng tr\u00ecnh luy\u1ec7n SAT<\/span><\/a><span style=\"font-weight: 400;\"> theo n\u0103ng l\u1ef1c \u0111\u1ea7u v\u00e0o v\u00e0 m\u1ee5c ti\u00eau \u0111i\u1ec3m s\u1ed1 c\u1ee7a t\u1eebng h\u1ecdc sinh, ch\u00fa tr\u1ecdng c\u1ee7ng c\u1ed1 ki\u1ebfn th\u1ee9c, r\u00e8n luy\u1ec7n chi\u1ebfn l\u01b0\u1ee3c l\u00e0m b\u00e0i v\u00e0 theo d\u00f5i ti\u1ebfn \u0111\u1ed9 h\u1ecdc t\u1eadp. Li\u00ean h\u1ec7 ETEST \u0111\u1ec3 \u0111\u01b0\u1ee3c t\u01b0 v\u1ea5n l\u1ed9 tr\u00ecnh luy\u1ec7n SAT ph\u00f9 h\u1ee3p, gi\u00fap b\u1ea1n chu\u1ea9n b\u1ecb t\u1ed1t h\u01a1n cho k\u1ef3 thi v\u00e0 k\u1ebf ho\u1ea1ch du h\u1ecdc trong t\u01b0\u01a1ng lai.<\/span><\/p>\n<figure id=\"attachment_34148\" aria-describedby=\"caption-attachment-34148\" style=\"width: 711px\" class=\"wp-caption aligncenter\"><img decoding=\"async\" class=\"wp-image-34148 size-medium\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12-711x400.jpg\" alt=\"\" width=\"711\" height=\"400\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12-711x400.jpg 711w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12-1400x788.jpg 1400w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12-768x432.jpg 768w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12-1536x864.jpg 1536w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12-18x10.jpg 18w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/CHEN-LOGO-CHO-ANH-4-12.jpg 1920w\" sizes=\"(max-width: 711px) 100vw, 711px\" \/><figcaption id=\"caption-attachment-34148\" class=\"wp-caption-text\">ETEST \u0111\u1ecbnh h\u01b0\u1edbng ch\u01b0\u01a1ng tr\u00ecnh luy\u1ec7n SAT theo n\u0103ng l\u1ef1c \u0111\u1ea7u v\u00e0o v\u00e0 m\u1ee5c ti\u00eau \u0111i\u1ec3m s\u1ed1 c\u1ee7a t\u1eebng h\u1ecdc sinh, ch\u00fa tr\u1ecdng c\u1ee7ng c\u1ed1 ki\u1ebfn th\u1ee9c, r\u00e8n luy\u1ec7n chi\u1ebfn l\u01b0\u1ee3c l\u00e0m b\u00e0i v\u00e0 theo d\u00f5i ti\u1ebfn \u0111\u1ed9 h\u1ecdc t\u1eadp.<\/figcaption><\/figure>\n<h2><b>C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p v\u1ec1 Chord of a Circle:<\/b><\/h2>\n<h3><b>Chord of a Circle l\u00e0 g\u00ec?<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">Chord of a Circle l\u00e0 \u0111o\u1ea1n th\u1eb3ng n\u1ed1i hai \u0111i\u1ec3m b\u1ea5t k\u1ef3 tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n. \u0110\u01b0\u1eddng k\u00ednh l\u00e0 d\u00e2y cung \u0111\u1eb7c bi\u1ec7t \u0111i qua t\u00e2m.<\/span><\/p>\n<h3><b>C\u00f4ng th\u1ee9c t\u00ednh \u0111\u1ed9 d\u00e0i d\u00e2y cung l\u00e0 g\u00ec?<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">N\u1ebfu bi\u1ebft b\u00e1n k\u00ednh <\/span><span style=\"font-weight: 400;\">r<\/span><span style=\"font-weight: 400;\"> v\u00e0 kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung <\/span><span style=\"font-weight: 400;\">h<\/span><span style=\"font-weight: 400;\">, c\u00f4ng th\u1ee9c l\u00e0:<\/span><\/p>\n<p><img decoding=\"async\" class=\"alignnone size-full wp-image-34136\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1.png\" alt=\"\" width=\"131\" height=\"73\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1.png 131w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/3-1-18x10.png 18w\" sizes=\"(max-width: 131px) 100vw, 131px\" \/><\/p>\n<p><span style=\"font-weight: 400;\">N\u1ebfu bi\u1ebft g\u00f3c \u1edf t\u00e2m <\/span><span style=\"font-weight: 400;\">, c\u00f4ng th\u1ee9c l\u00e0:<\/span><\/p>\n<p><span style=\"font-weight: 400;\"><img decoding=\"async\" class=\"alignnone size-full wp-image-34137\" src=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1.png\" alt=\"\" width=\"174\" height=\"71\" srcset=\"https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1.png 174w, https:\/\/etest.edu.vn\/wp-content\/uploads\/2026\/10\/4-1-18x7.png 18w\" sizes=\"(max-width: 174px) 100vw, 174px\" \/><\/span><\/p>\n<h3><b>D\u00e2y cung d\u00e0i nh\u1ea5t c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 g\u00ec?<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">\u0110\u01b0\u1eddng k\u00ednh l\u00e0 d\u00e2y cung d\u00e0i nh\u1ea5t c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n, c\u00f3 \u0111\u1ed9 d\u00e0i b\u1eb1ng hai l\u1ea7n b\u00e1n k\u00ednh.<\/span><\/p>\n<h3><b>\u0110\u01b0\u1eddng vu\u00f4ng g\u00f3c t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung c\u00f3 t\u00ednh ch\u1ea5t g\u00ec?<\/b><\/h3>\n<p><span style=\"font-weight: 400;\">\u0110\u01b0\u1eddng vu\u00f4ng g\u00f3c k\u1ebb t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung s\u1ebd \u0111i qua trung \u0111i\u1ec3m c\u1ee7a d\u00e2y cung, chia d\u00e2y th\u00e0nh hai \u0111o\u1ea1n b\u1eb1ng nhau.<\/span><\/p>\n<p>&nbsp;<\/p>\n\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-left kksr-valign-bottom\"\n    data-payload='{&quot;align&quot;:&quot;left&quot;,&quot;id&quot;:&quot;34132&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;bottom&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;836&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;5&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;\u0110\u00e1nh gi\u00e1 b\u00e0i vi\u1ebft&quot;,&quot;legend&quot;:&quot;5\\\/5 - (836 votes)&quot;,&quot;size&quot;:&quot;24&quot;,&quot;title&quot;:&quot;Chord of a Circle l\u00e0 g\u00ec? C\u00f4ng th\u1ee9c, t\u00ednh ch\u1ea5t d\u00e2y cung v\u00e0 b\u00e0i t\u1eadp minh h\u1ecda&quot;,&quot;width&quot;:&quot;142.5&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} - ({count} {votes})&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 142.5px;\">\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-right: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 24px; height: 24px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 19.2px;\">\n            5\/5 - (836 votes)    <\/div>\n    <\/div>","protected":false},"excerpt":{"rendered":"<p>Chord of a Circle l\u00e0 g\u00ec? C\u00f4ng th\u1ee9c, t\u00ednh ch\u1ea5t d\u00e2y cung v\u00e0 b\u00e0i t\u1eadp minh h\u1ecda Trong h\u00ecnh h\u1ecdc, Chord of a Circle (d\u00e2y cung c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n) l\u00e0 m\u1ed9t kh\u00e1i ni\u1ec7m quan tr\u1ecdng, th\u01b0\u1eddng xu\u1ea5t hi\u1ec7n trong c\u00e1c b\u00e0i to\u00e1n v\u1ec1 \u0111\u1ed9 d\u00e0i, kho\u1ea3ng c\u00e1ch t\u1eeb t\u00e2m \u0111\u1ebfn d\u00e2y cung v\u00e0 quan h\u1ec7 [&#8230;]","protected":false},"author":24,"featured_media":34149,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":""},"categories":[1,285],"tags":[],"class_list":["post-34132","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-tin-tuc","category-sat"],"acf":[],"_links":{"self":[{"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/posts\/34132","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/comments?post=34132"}],"version-history":[{"count":1,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/posts\/34132\/revisions"}],"predecessor-version":[{"id":34150,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/posts\/34132\/revisions\/34150"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/media\/34149"}],"wp:attachment":[{"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/media?parent=34132"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/categories?post=34132"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/etest.edu.vn\/en\/wp-json\/wp\/v2\/tags?post=34132"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}