{"id":1129,"date":"2021-10-08T13:18:30","date_gmt":"2021-10-08T13:18:30","guid":{"rendered":"https:\/\/www.vietlearn.org\/post\/?p=1129"},"modified":"2021-10-14T22:11:31","modified_gmt":"2021-10-14T15:11:31","slug":"su-xac-dinh-duong-tron-tinh-chat-doi-xung-cua-duong-tron-hoc-hinh-9","status":"publish","type":"post","link":"https:\/\/www.vietlearn.org\/kien-thuc\/su-xac-dinh-duong-tron-tinh-chat-doi-xung-cua-duong-tron-hoc-hinh-9\/","title":{"rendered":"S\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u2013 H\u1ecdc h\u00ecnh 9"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Ghi ch\u00fa: T\u00e0i li\u1ec7u tr\u00edch d\u1eabn<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Trong h\u00ecnh h\u1ecdc th\u00ec b\u00e0i to\u00e1n v\u1ec1 \u0111\u01b0\u1eddng tr\u00f2n h\u1ebft s\u1ee9c ph\u1ed5 bi\u1ebfn, \u0111\u1eb7c bi\u1ec7t l\u00e0 trong c\u00e1c k\u1ef3 thi. Ch\u00ednh v\u00ec v\u1eady s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 m\u1ed9t trong nh\u1eefng ki\u1ebfn th\u1ee9c c\u1ea7n ph\u1ea3i n\u1eafm v\u1eefng. Qua b\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y ch\u00fang t\u00f4i s\u1ebd t\u1ed5ng h\u1ee3p l\u1ea1i cho c\u00e1c b\u1ea1n nh\u1eefng <a href=\"https:\/\/www.vietlearn.org\" data-internallinksmanager029f6b8e52c=\"2\" title=\"Vietlearn\" rel=\"nofollow\">ki\u1ebfn th\u1ee9c c\u01a1 b\u1ea3n<\/a> v\u00e0 c\u00e1c d\u1ea1ng b\u00e0i t\u1eadp c\u00f3 li\u00ean quan.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ki\u1ebfn th\u1ee9c c\u1ea7n nh\u1edb<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u1ede m\u00f4n to\u00e1n 9 s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 m\u1ed9t ki\u1ebfn th\u1ee9c kh\u00e1 quan tr\u1ecdng. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 nh\u1eefng <a href=\"https:\/\/www.vietlearn.org\" data-internallinksmanager029f6b8e52c=\"2\" title=\"Vietlearn\" rel=\"nofollow\">ki\u1ebfn th\u1ee9c c\u01a1 b\u1ea3n<\/a> ch\u00fang ta c\u1ea7n n\u1eafm v\u1eefng v\u1ec1 b\u00e0i h\u1ecdc \u0111\u1ec3 c\u00f3 th\u1ec3 gi\u1ea3i \u0111\u01b0\u1ee3c nh\u1eefng b\u00e0i t\u1eadp.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Chuy\u00ean \u0111\u1ec1 v\u1ec1 S\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n l\u00e0 t\u1eadp h\u1ee3p nh\u1eefng \u0111i\u1ec3m c\u00e1ch \u0111i\u1ec3m c\u1ed1 \u0111\u1ecbnh O m\u1ed9t kho\u1ea3ng kh\u00f4ng \u0111\u1ed5i g\u1ecdi l\u00e0 \u0111i\u1ec3m R (R&gt;0), \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 b\u00e1n k\u00ednh R t\u00e2m O.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">K\u00ed hi\u1ec7u: (O;R) ho\u1eb7c (O).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u1ecb tr\u00ed t\u01b0\u01a1ng \u0111\u1ed1i<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n (O) h\u1ec7 th\u1ee9c OM=R<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M n\u1eb1m trong \u0111\u01b0\u1eddng tr\u00f2n (O) h\u1ec7 th\u1ee9c OM&lt; R<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n (O) h\u1ec7 th\u1ee9c OM&gt;R<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u1ecbnh l\u00fd v\u1ec1 s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n v\u00e0 t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u1ecbnh l\u00fd v\u1ec1 s\u1ef1 x\u00e1c \u0111\u1ecbnh c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Qua 3 \u0111i\u1ec3m kh\u00f4ng th\u1eb3ng h\u00e0ng, ch\u00fang ta ch\u1ec9 c\u00f3 th\u1ec3 v\u1ebd \u0111\u01b0\u1ee3c duy nh\u1ea5t m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n \u0111i qua c\u00e1c \u0111\u1ec9nh c\u1ee7a tam gi\u00e1c th\u00ec g\u1ecdi l\u00e0 \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp c\u1ee7a tam gi\u00e1c \u0111\u00f3. T\u00e2m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp ch\u00ednh l\u00e0 giao c\u1ee7a 3 \u0111\u01b0\u1eddng trung tr\u1ef1c tam gi\u00e1c.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n l\u00e0 h\u00ecnh c\u00f3 t\u00e2m \u0111\u1ed1i x\u1ee9ng. T\u00e2m \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n ch\u00ednh l\u00e0 t\u00e2m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n c\u00f3 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng. \u0110\u01b0\u1eddng k\u00ednh c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n ch\u00ednh l\u00e0 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n c\u00f3 bao nhi\u00eau tr\u1ee5c \u0111\u1ed1i x\u1ee9ng?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e1c d\u1ea1ng to\u00e1n th\u01b0\u1eddng g\u1eb7p<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00f3 3 d\u1ea1ng b\u00e0i t\u1eadp v\u1ec1 s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n m\u00e0 ch\u00fang ta th\u01b0\u1eddng hay g\u1eb7p \u0111\u00f3 l\u00e0:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D\u1ea1ng 1: Ch\u1ee9ng minh nh\u1eefng \u0111i\u1ec3m \u0111\u00e3 cho tr\u01b0\u1edbc c\u00f9ng thu\u1ed9c trong m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ph\u01b0\u01a1ng ph\u00e1p: \u0111\u1ec3 ch\u1ee9ng minh nh\u1eefng \u0111i\u1ec3m cho tr\u01b0\u1edbc c\u00f9ng c\u00e1ch \u0111\u1ec1u m\u1ed9t \u0111i\u1ec3m. \u0110i\u1ec3m \u0111\u00f3 l\u00e0 t\u00e2m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D\u1ea1ng 2: X\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1ee3c v\u1ecb tr\u00ed t\u01b0\u01a1ng \u0111\u1ed1i c\u1ee7a m\u1ed9t \u0111i\u1ec3m v\u1edbi m\u1ed9t \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ph\u01b0\u01a1ng ph\u00e1p: \u0110\u1ec3 x\u00e1c \u0111\u1ecbnh v\u1ecb tr\u00ed t\u01b0\u01a1ng \u0111\u1ed1i c\u1ee7a \u0111i\u1ec3m M v\u1edbi \u0111\u01b0\u1eddng tr\u00f2n (O;R) ch\u00fang ta s\u1ebd so s\u00e1nh kho\u1ea3ng c\u00e1ch c\u1ee7a OM v\u1edbi b\u00e1n k\u00ednh R theo c\u00e1ch sau:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n (O) h\u1ec7 th\u1ee9c OM=R<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M n\u1eb1m trong \u0111\u01b0\u1eddng tr\u00f2n (O) h\u1ec7 th\u1ee9c OM&lt; R<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">M n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n (O) h\u1ec7 th\u1ee9c OM&gt;R<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D\u1ea1ng 3: t\u00ednh b\u00e1n k\u00ednh v\u00e0 x\u00e1c \u0111\u1ecbnh t\u00e2m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">X\u00e1c \u0111\u1ecbnh t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ph\u01b0\u01a1ng ph\u00e1p: Ta s\u1ebd d\u00f9ng nh\u1eefng c\u00e1c ki\u1ebfn th\u1ee9c sau:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">S\u1eed d\u1ee5ng t\u00ednh ch\u1ea5t v\u1ec1 \u0111\u01b0\u1eddng trung tuy\u1ebfn trong tam gi\u00e1c vu\u00f4ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D\u00f9ng \u0111\u1ecbnh l\u00fd Pytago.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">S\u1eed d\u1ee5ng h\u1ec7 th\u1ee9c l\u01b0\u1ee3ng v\u1ec1 c\u1ea1nh v\u00e0 c\u00e1c g\u00f3c trong tam gi\u00e1c vu\u00f4ng.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p> \u0110\u01b0\u1eddng k\u00ednh v\u00e0 d\u00e2y c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p><\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Nh\u1eefng d\u1ea1ng b\u00e0i t\u1eadp th\u01b0\u1eddng g\u1eb7p v\u1ec1 s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">D\u01b0\u1edbi \u0111\u00e2y l\u00e0 10 b\u00e0i t\u1eadp d\u1ea1ng ph\u1ed5 bi\u1ebfn nh\u1ea5t v\u1ec1 s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 1: S\u1ed1 t\u00e2m \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n l\u00e0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A. 1 B. 2<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C. 3 D. 4<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: \u0110\u01b0\u1eddng tr\u00f2n l\u00e0 h\u00ecnh c\u00f3 t\u00e2m \u0111\u1ed1i x\u1ee9ng. T\u00e2m \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 t\u00e2m \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111\u00f3.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u00ean \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 m\u1ed9t t\u00e2m \u0111\u1ed1i x\u1ee9ng duy nh\u1ea5t l\u00e0 t\u00e2m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n A<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 2: Kh\u1eb3ng \u0111\u1ecbnh n\u00e0o sau \u0111\u00e2y l\u00e0 \u0111\u00fang khi n\u00f3i v\u1ec1 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n kh\u00f4ng c\u00f3 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n c\u00f3 duy nh\u1ea5t m\u1ed9t tr\u1ee5c \u0111\u1ed1i x\u1ee9ng l\u00e0 \u0111\u01b0\u1eddng k\u00ednh<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n c\u00f3 hai tr\u1ee5c \u0111\u1ed1i x\u1ee9ng l\u00e0 hai \u0111\u01b0\u1eddng k\u00ednh vu\u00f4ng g\u00f3c v\u1edbi nhau<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110\u01b0\u1eddng tr\u00f2n c\u00f3 v\u00f4 s\u1ed1 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng l\u00e0 \u0111\u01b0\u1eddng k\u00ednh<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: \u0110\u01b0\u1eddng tr\u00f2n l\u00e0 h\u00ecnh c\u00f3 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng. B\u1ea5t k\u00ec \u0111\u01b0\u1eddng k\u00ednh n\u00e0o c\u0169ng l\u00e0 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u00ean \u0111\u01b0\u1eddng tr\u00f2n c\u00f3 v\u00f4 s\u1ed1 tr\u1ee5c \u0111\u1ed1i x\u1ee9ng<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n D.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 3: T\u00e2m c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp tam gi\u00e1c l\u00e0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Giao c\u1ee7a ba \u0111\u01b0\u1eddng ph\u00e2n gi\u00e1c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Giao c\u1ee7a ba \u0111\u01b0\u1eddng trung tr\u1ef1c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Giao c\u1ee7a ba \u0111\u01b0\u1eddng cao<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Giao c\u1ee7a ba \u0111\u01b0\u1eddng trung tuy\u1ebfn<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: T\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp tam gi\u00e1c l\u00e0 giao \u0111i\u1ec3m c\u1ee7a ba \u0111\u01b0\u1eddng trung tr\u1ef1c c\u1ee7a tam gi\u00e1c \u0111\u00f3<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n B.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 4: Cho \u0111\u01b0\u1eddng tr\u00f2n (O; R) v\u00e0 \u0111i\u1ec3m M b\u1ea5t k\u00ec, bi\u1ebft r\u1eb1ng OM = R . Ch\u1ecdn kh\u1eb3ng \u0111\u1ecbnh \u0111\u00fang?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec3m M n\u1eb1m ngo\u00e0i \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec3m M n\u1eb1m tr\u00ean \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec3m M n\u1eb1m trong \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec3m M kh\u00f4ng thu\u1ed9c \u0111\u01b0\u1eddng tr\u00f2n<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: Cho \u0111i\u1ec3m M v\u00e0 \u0111\u01b0\u1eddng tr\u00f2n (O; R) ta so s\u00e1nh kho\u1ea3ng c\u00e1ch OM v\u1edbi b\u00e1n k\u00ednh R \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh v\u1ecb tr\u00ed t\u01b0\u01a1ng \u0111\u1ed1i theo b\u1ea3ng sau:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n B.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 5: X\u00e1c \u0111\u1ecbnh t\u00e2m v\u00e0 b\u00e1n k\u00ednh c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n \u0111i qua c\u1ea3 b\u1ed1n \u0111\u1ec9nh c\u1ee7a h\u00ecnh vu\u00f4ng ABCD c\u1ea1nh a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u00e2m l\u00e0 giao \u0111i\u1ec3m A v\u00e0 b\u00e1n k\u00ednh R = a\u221a2<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u00e2m l\u00e0 giao \u0111i\u1ec3m hai \u0111\u01b0\u1eddng ch\u00e9o v\u00e0 b\u00e1n k\u00ednh R = a\u221a2<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u00e2m l\u00e0 giao \u0111i\u1ec3m hai \u0111\u01b0\u1eddng ch\u00e9o v\u00e0 b\u00e1n k\u00ednh<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u00e2m l\u00e0 \u0111i\u1ec3m B v\u00e0 b\u00e1n k\u00ednh l\u00e0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">G\u1ecdi O l\u00e0 giao hai \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a h\u00ecnh vu\u00f4ng ABCD.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Khi \u0111\u00f3 theo t\u00ednh ch\u1ea5t c\u1ee7a h\u00ecnh vu\u00f4ng ta c\u00f3 OA = OB = OC = OD n\u00ean O l\u00e0 t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp h\u00ecnh vu\u00f4ng ABCD, b\u00e1n k\u00ednh R = OA = AC\/2<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">X\u00e9t tam gi\u00e1c vu\u00f4ng t\u1ea1i ta c\u00f3:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">V\u1eady t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp h\u00ecnh vu\u00f4ng ABCD c\u1ea1nh a l\u00e0 giao \u0111i\u1ec3m hai \u0111\u01b0\u1eddng ch\u00e9o, b\u00e1n k\u00ednh l\u00e0<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n C.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 6: Cho tam gi\u00e1c ABC vu\u00f4ng t\u1ea1i A. Khi \u0111\u00f3, t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp tam gi\u00e1c ABC l\u00e0?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u0110i\u1ec3m A B. \u0110i\u1ec3m B<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C. Ch\u00e2n \u0111\u01b0\u1eddng cao h\u1ea1 t\u1eeb A D. Trung \u0111i\u1ec3m c\u1ee7a BC<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: G\u1ecdi M l\u00e0 trung \u0111i\u1ec3m c\u1ee7a BC.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Tam gi\u00e1c ABC vu\u00f4ng t\u1ea1i A c\u00f3 \u0111\u01b0\u1eddng trung tuy\u1ebfn AM \u1ee9ng v\u1edbi c\u1ea1nh huy\u1ec1n BC n\u00ean:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Suy ra, \u0111i\u1ec3m M l\u00e0 t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp tam gi\u00e1c ABC<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n D.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 7: Cho t\u1ee9 gi\u00e1c ABCD l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh v\u00e0 vu\u00f4ng t\u1ea1i A. T\u00ecm t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp t\u1ee9 gi\u00e1c ABCD?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A. Trung \u0111i\u1ec3m AC B . \u0110i\u1ec3m A<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C. \u0110i\u1ec3m B D. \u0110i\u1ec3m D<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: V\u00ec t\u1ee9 gi\u00e1c ABCD l\u00e0 h\u00ecnh b\u00ecnh h\u00e0nh v\u00e0 n\u00ean ABCD l\u00e0 h\u00ecnh ch\u1eef nh\u1eadt.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">G\u1ecdi O l\u00e0 giao \u0111i\u1ec3m hai \u0111\u01b0\u1eddng ch\u00e9o.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Theo t\u00ednh ch\u1ea5t h\u00ecnh ch\u1eef nh\u1eadt ta c\u00f3:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Do \u0111\u00f3, O l\u00e0 t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp h\u00ecnh ch\u1eef nh\u1eadt ABCD.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n A.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 8: Cho 4 \u0111i\u1ec3m ph\u00e2n bi\u1ec7t A, B, C v\u00e0 D sao cho tam gi\u00e1c ABC vu\u00f4ng t\u1ea1i A v\u00e0 tam gi\u00e1c BCD vu\u00f4ng t\u1ea1i D. T\u00ecm t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp t\u1ee9 gi\u00e1c ABCD?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u0110i\u1ec3m A B. \u0110i\u1ec3m B<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C. Trung \u0111i\u1ec3m BC D. Trung \u0111i\u1ec3m AD<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: G\u1ecdi I l\u00e0 trung \u0111i\u1ec3m BC.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ta c\u00f3; tam gi\u00e1c BCD vu\u00f4ng t\u1ea1i D c\u00f3 DI l\u00e0 \u0111\u01b0\u1eddng trung tuy\u1ebfn \u1ee9ng v\u1edbi c\u1ea1nh huy\u1ec1n BC n\u00ean:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Tam gi\u00e1c ABC vu\u00f4ng t\u1ea1i A c\u00f3 AI l\u00e0 \u0111\u01b0\u1eddng trung tuy\u1ebfn \u1ee9ng v\u1edbi c\u1ea1nh huy\u1ec1n BC n\u00ean:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u1eeb (1) v\u00e0 (2) suy ra:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Do \u0111\u00f3, I l\u00e0 t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp t\u1ee9 gi\u00e1c ABCD.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n C<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 9: Cho h\u00ecnh thoi ABCD c\u00f3 AC = BD. T\u00ecm t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp h\u00ecnh thoi ABCD?<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u0110i\u1ec3m A.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Giao \u0111i\u1ec3m c\u1ee7a AC v\u00e0 BD<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Kh\u00f4ng c\u00f3 \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp t\u1ee9 gi\u00e1c ABCD.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Trung \u0111i\u1ec3m c\u1ea1nh AB.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: V\u00ec t\u1ee9 gi\u00e1c ABCD l\u00e0 h\u00ecnh thoi c\u00f3 2 \u0111\u01b0\u1eddng ch\u00e9o AC= BD n\u00ean t\u1ee9 gi\u00e1c ABCD l\u00e0 h\u00ecnh vu\u00f4ng ( d\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft h\u00ecnh vu\u00f4ng)..<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">G\u1ecdi O l\u00e0 t\u00e2m h\u00ecnh vu\u00f4ng.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Theo t\u00ednh ch\u1ea5t h\u00ecnh vu\u00f4ng ta c\u00f3:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Do \u0111\u00f3, O l\u00e0 t\u00e2m \u0111\u01b0\u1eddng tr\u00f2n ngo\u1ea1i ti\u1ebfp h\u00ecnh vu\u00f4ng ABCD.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n B<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00e2u 10: H\u00ecnh tr\u00f2n t\u00e2m I, b\u00e1n k\u00ednh R = 4cm l\u00e0 g\u1ed3m t\u1ea5t c\u1ea3 c\u00e1c \u0111i\u1ec3m \u2026\u2026..<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">c\u00f3 kho\u1ea3ng c\u00e1ch \u0111\u1ebfn \u0111i\u1ec3m I b\u1eb1ng 4cm<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00f3 kho\u1ea3ng c\u00e1ch \u0111\u1ebfn \u0111i\u1ec3m I nh\u1ecf h\u01a1n 4 cm.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">C\u00f3 kho\u1ea3ng c\u00e1ch \u0111\u1ebfn \u0111i\u1ec3m I l\u1edbn h\u01a1n 4 cm.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">c\u00f3 kho\u1ea3ng c\u00e1ch \u0111\u1ebfn \u0111i\u1ec3m I nh\u1ecf h\u01a1n ho\u1eb7c b\u1eb1ng 4 cm.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">L\u1eddi gi\u1ea3i: H\u00ecnh tr\u00f2n t\u00e2m I, b\u00e1n k\u00ednh R = 4cm l\u00e0 g\u1ed3m t\u1ea5t c\u1ea3 c\u00e1c \u0111i\u1ec3m c\u00f3 kho\u1ea3ng c\u00e1ch \u0111\u1ebfn \u0111i\u1ec3m I nh\u1ecf h\u01a1n ho\u1eb7c b\u1eb1ng 4 cm.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ch\u1ecdn \u0111\u00e1p \u00e1n D.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B\u00e0i vi\u1ebft tr\u00ean \u0111\u00e2y l\u00e0 nh\u1eefng <a href=\"https:\/\/www.vietlearn.org\" data-internallinksmanager029f6b8e52c=\"2\" title=\"Vietlearn\" rel=\"nofollow\">ki\u1ebfn th\u1ee9c c\u01a1 b\u1ea3n<\/a> v\u00e0 b\u00e0i t\u1eadp v\u1ec1 v\u1ec1 s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n. N\u1ebfu b\u1ea1n c\u00f2n c\u00f3 c\u00e2u h\u1ecfi g\u00ec c\u1ea7n gi\u1ea3i \u0111\u00e1p hay mu\u1ed1n \u0111\u0103ng k\u00fd tham gia c\u00e1c kh\u00f3a h\u1ecdc th\u00ec c\u00f3 th\u1ec3 li\u00ean h\u1ec7 tr\u1ef1c ti\u1ebfp v\u1edbi ch\u00fang t\u00f4i th\u00f4ng qua s\u1ed1 Hotline: +84 96-6989-538 ho\u1eb7c t\u1ea1i \u0111\u1ecba ch\u1ec9 website: Vietlearn.org\/ \u0111\u1ec3 \u0111\u01b0\u1ee3c gi\u1ea3i \u0111\u00e1p m\u1ed9t c\u00e1ch t\u1eadn t\u00ecnh, chu \u0111\u00e1o nh\u1ea5t.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u00ecm hi\u1ec3u th\u00eam:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">B\u1ea3ng l\u01b0\u1ee3ng gi\u00e1c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">T\u1ee9 gi\u00e1c n\u1ed9i ti\u1ebfp \u0111\u01b0\u1eddng tr\u00f2n \u2013 H\u1ecdc t\u1ed1t To\u00e1n 9 c\u00f9ng T<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"<p>Ghi ch\u00fa: T\u00e0i li\u1ec7u tr\u00edch d\u1eabn Trong h\u00ecnh h\u1ecdc th\u00ec b\u00e0i to\u00e1n v\u1ec1 \u0111\u01b0\u1eddng tr\u00f2n h\u1ebft s\u1ee9c ph\u1ed5 bi\u1ebfn, \u0111\u1eb7c bi\u1ec7t l\u00e0 trong c\u00e1c k\u1ef3 thi. Ch\u00ednh v\u00ec v\u1eady s\u1ef1 x\u00e1c \u0111\u1ecbnh \u0111\u01b0\u1eddng tr\u00f2n t\u00ednh ch\u1ea5t \u0111\u1ed1i x\u1ee9ng c\u1ee7a \u0111\u01b0\u1eddng tr\u00f2n l\u00e0 m\u1ed9t trong nh\u1eefng ki\u1ebfn th\u1ee9c c\u1ea7n ph\u1ea3i n\u1eafm v\u1eefng. Qua b\u00e0i vi\u1ebft d\u01b0\u1edbi [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[9,4],"tags":[],"class_list":["post-1129","post","type-post","status-publish","format-standard","hentry","category-toan-hoc","category-trung-hoc"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/1129","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=1129"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/1129\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=1129"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=1129"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=1129"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}