Th\u00f4ng th\u01b0\u1eddng khi \u0111i trong m\u01b0a ng\u01b0\u1eddi ta c\u1ed1 g\u1eafng ch\u1ea1y th\u1eadt nhanh v\u00ec cho r\u1eb1ng \u0111i c\u00e0ng nhanh th\u00ec c\u00e0ng \u00edt b\u1ecb \u01b0\u1edbt \u0111\u1eabm n\u01b0\u1edbc m\u01b0a. Th\u1ef1c t\u1ebf c\u00f3 ph\u1ea3i nh\u01b0 v\u1eady kh\u00f4ng?<\/p>\n\n\n\n
Gi\u1ea3 s\u1eed th\u00e2n ng\u01b0\u1eddi l\u00e0 m\u1ed9t c\u1ed9t vu\u00f4ng d\u00e0i th\u00ec, di\u1ec7n t\u00edch c\u1ee7a c\u00e1c m\u1eb7t tr\u01b0\u1edbc, m\u1eb7t b\u00ean v\u00e0 \u0111\u1ec9nh \u0111\u1ea7u t\u1ec9 l\u1ec7 1: a: b, th\u00e2n ng\u01b0\u1eddi chuy\u1ec3n \u0111\u1ed9ng theo ph\u01b0\u01a1ng tr\u1ee5c x v\u1edbi t\u1ed1c \u0111\u1ed9 v, \u0111o\u1ea1n \u0111\u01b0\u1eddng di chuy\u1ec3n l\u00e0 L.<\/p>\n\n\n\n
Gi\u1ea3 s\u1eed m\u01b0a r\u01a1i v\u1edbi v\u1eadn t\u1ed1c u c\u00f3 c\u00e1c th\u00e0nh ph\u1ea7n t\u1ed1c \u0111\u1ed9 theo c\u00e1c tr\u1ee5c Ox, Oy, tr\u00ean m\u1eb7t b\u1eb1ng v\u00e0 tr\u1ee5c th\u1eb3ng \u0111\u1ee9ng Oz l\u00e0 Ux, Uy, Uz.<\/p>\n\n\n\n
Trong \u0111\u01a1n v\u1ecb th\u1eddi gian, n\u01b0\u1edbc m\u01b0a r\u01a1i v\u00e0o tr\u01b0\u1edbc m\u1eb7t, m\u1eb7t b\u00ean v\u00e0 \u0111\u1ec9nh \u0111\u1ea7u l\u00e0m \u01b0\u1edbt \u0111\u1eabm n\u01b0\u1edbc m\u01b0a, c\u00f3 li\u00ean quan \u0111\u1ebfn di\u1ec7n t\u00edch c\u00e1c m\u1eb7t, ph\u01b0\u01a1ng h\u01b0\u1edbng chuy\u1ec3n \u0111\u1ed9ng v\u00e0 t\u1ed1c \u0111\u1ed9 tuy\u1ec7t \u0111\u1ed1i c\u1ee7a n\u01b0\u1edbc m\u01b0a, v\u00ec v\u1eady trong \u0111\u01a1n v\u1ecb th\u1eddi gian th\u00ec \u0111\u1ed9 \u0111\u1eabm n\u01b0\u1edbc m\u01b0a c\u00f3 th\u1ec3 bi\u1ec3u di\u1ec5n b\u1eb1ng: trong \u0111\u00f3, K l\u00e0 h\u1ec7 s\u1ed1 t\u1ec9 l\u1ec7. V\u00ec v\u1eady trong kho\u1ea3ng th\u1eddi gian 1\/v, t\u1ed5ng l\u01b0\u1ee3ng n\u01b0\u1edbc m\u01b0a \u01b0\u1edbt \u0111\u1eabm v\u00e0o ng\u01b0\u1eddi s\u1ebd b\u1eb1ng:<\/p>\n\n\n\n
Trong \u0111\u00f3, v l\u00e0 bi\u1ebfn s\u1ed1, S l\u00e0 c\u00e1c \u0111\u1ea1i l\u01b0\u1ee3ng ph\u1ee5 thu\u1ed9c v. Sau \u0111\u00e2y ta s\u1ebd x\u00e9t c\u00e1c tr\u01b0\u1eddng h\u1ee3p khi v < Ux, t\u1ee9c khi v\u1eadn t\u1ed1c ng\u01b0\u1eddi nh\u1ecf h\u01a1n t\u1ed1c \u0111\u1ed9 c\u1ee7a m\u01b0a<\/p>\n\n\n\n
Hi\u1ec3n nhi\u00ean v c\u00e0ng l\u1edbn th\u00ec S(v) c\u00e0ng b\u00e9 hay n\u00f3i c\u00e1ch kh\u00e1c, trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y th\u00ec \u0111i c\u00e0ng nhanh c\u00e0ng b\u1ecb \u01b0\u1edbt \u0111\u1eabm n\u01b0\u1edbc m\u01b0a.<\/p>\n\n\n\n
C\u0169ng theo c\u00f4ng th\u1ee9c tr\u00ean ch\u00fang ta c\u00f3 th\u1ec3 t\u00ecm th\u1ea5y v \u2265 uv, n\u1ebfu Ux < a|ux| + b|uz| th\u00ec n\u1ebfu ch\u1ea1y c\u00e0ng nhanh c\u00e0ng \u00edt b\u1ecb \u0111\u1eabm n\u01b0\u1edbc m\u01b0a. Nh\u01b0ng n\u1ebfu Ux > a|ux| + b|uz| th\u00ec ch\u1ea1y c\u00e0ng nhanh c\u00e0ng \u0111\u1eabm nhi\u1ec1u n\u01b0\u1edbc m\u01b0a. Th\u1ef1c ra do trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y t\u1ed1c \u0111\u1ed9 c\u1ee7a m\u01b0a theo ph\u01b0\u01a1ng tr\u1ee5c x, l\u01b0\u1ee3ng m\u01b0a r\u01a1i v\u00e0o ng\u01b0\u1eddi ch\u1ee7 y\u1ebfu t\u1eeb ph\u01b0\u01a1ng n\u00e0y, v\u00ec th\u1ebf tr\u01b0\u1eddng h\u1ee3p n\u00e0y v kh\u00f4ng n\u00ean qu\u00e1 l\u1edbn. Tr\u00e1i l\u1ea1i trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y t\u1ed1c \u0111\u1ed9 di chuy\u1ec3n c\u1ee7a ng\u01b0\u1eddi v\u00e0 n\u01b0\u1edbc m\u01b0a b\u1eb1ng nhau t\u1ee9c l\u00e0 v = Ux th\u00ec l\u01b0\u1ee3ng n\u01b0\u1edbc m\u01b0a \u0111\u1ebfn t\u1eeb ph\u00eda tr\u01b0\u1edbc b\u1eb1ng 0.<\/p>\n\n\n\n
M\u1ecdi ng\u01b0\u1eddi \u0111\u1ec1u bi\u1ebft chi\u1ec1u cao c\u1ee7a ng\u01b0\u1eddi c\u00f3 li\u00ean quan ch\u1eb7t ch\u1ebd v\u1edbi t\u00ednh di truy\u1ec1n. Th\u00f4ng th\u01b0\u1eddng n\u1ebfu cha m\u1eb9 cao to th\u00ec sinh ra con c\u00e1i c\u0169ng c\u00f3 t\u1ea7m v\u00f3c cao to. Th\u1ebf nh\u01b0ng trong cu\u1ed9c s\u1ed1ng th\u01b0\u1eddng ng\u00e0y c\u0169ng c\u00f3 nhi\u1ec1u ngo\u1ea1i l\u1ec7. V\u00ec sao v\u1eady? k\u00ea.<\/p>\n\n\n\n
Sau \u0111\u00e2y ch\u00fang t\u00f4i xin tr\u00ecnh b\u00e0y m\u1ed9t s\u1ed1 kh\u00e1i ni\u1ec7m v\u1ec1 to\u00e1n th\u1ed1ng<\/p>\n\n\n\n
Gi\u1ea3 s\u1eed x1, x2,\u2026xn l\u00e0 chi\u1ec1u cao c\u1ee7a n ng\u01b0\u1eddi.<\/p>\n\n\n\n
Th\u1ebf th\u00ec chi\u1ec1u cao trung b\u00ecnh c\u1ee7a nh\u00f3m ng\u01b0\u1eddi n\u00e0y s\u1ebd l\u00e0 v\u00e0 \u0111\u1ed9 l\u1ec7ch qu\u00e2n ph\u01b0\u01a1ng<\/p>\n\n\n\n
Ph\u1ea3n \u00e1nh s\u1ef1 sai l\u1ec7ch c\u1ee7a c\u00e1c gi\u00e1 tr\u1ecb xi so v\u1edbi s\u1ed1 trung b\u00ecnh.<\/p>\n\n\n\n
\u0110\u1ec3 ph\u1ea3n \u00e1nh m\u1ed1i quan h\u1ec7 di truy\u1ec1n c\u1ee7a b\u1ed1 m\u1eb9 v\u00e0 con c\u00e1i v\u1ec1 ph\u01b0\u01a1ng di\u1ec7n t\u1ea7m v\u00f3c c\u01a1 th\u1ec3, ng\u01b0\u1eddi ta \u0111\u00e3 ti\u1ebfn h\u00e0nh nghi\u00ean c\u1ee9u 1000 \u0111\u00f4i cha con v\u1ec1 m\u1ed1i t\u01b0\u01a1ng quan chi\u1ec1u cao c\u1ee7a h\u1ecd. Gi\u1ea3 s\u1eed x v\u00e0 y bi\u1ec3u di\u1ec5n chi\u1ec1u cao c\u1ee7a cha v\u00e0 con, v\u00e0 ch\u1ecdn x l\u00e0 chi\u1ec1u cao c\u1ee7a b\u1ed1 \u0111\u1eb7t tr\u00ean tr\u1ee5c ho\u00e0nh, c\u00f2n y l\u00e0 chi\u1ec1u cao c\u1ee7a con \u0111\u1eb7t tr\u00ean tr\u1ee5c y. \u0110\u1eb7t c\u00e1c c\u1eb7p s\u1ed1 (xi, yi) tr\u00ean to\u1ea1 \u0111\u1ed9 ph\u1eb3ng (i – 1,\u2026,1000) ta c\u00f3 th\u1ec3 t\u00ecm th\u1ea5y to\u00e0n b\u1ed9 quang c\u1ea3nh c\u1ee7a m\u1ed1i li\u00ean quan n\u00e0y b\u1eb1ng \u0111\u00e1m t\u01b0\u01a1ng quan c\u00f3 d\u1ea1ng h\u00ecnh b\u1ea7u d\u1ee5c, h\u00ecnh b\u1ea7u d\u1ee5c c\u00f3 tr\u1ee5c nghi\u00eang 45o.<\/p>\n\n\n\n
V\u00ec v\u1eady \u0111\u01b0\u1eddng bi\u1ec3u di\u1ec5n \u0111\u1ed9 t\u1ea3n m\u1ea1n SD s\u1ebd l\u00e0 \u0111\u01b0\u1eddng th\u1eb3ng c\u1eaft tr\u1ee5c ho\u00e0nh m\u1ed9t g\u00f3c 45o. V\u00e0 b\u1edfi v\u00ec so v\u1edbi cha th\u00ec con th\u01b0\u1eddng cao h\u01a1n cha kho\u1ea3ng 2 cm v\u00e0 \u0111\u01b0\u1eddng bi\u1ec3u di\u1ec5n \u0111\u1ed9 t\u1ea3n m\u1ea1n s\u1ebd xu\u1ea5t ph\u00e1t t\u1eeb \u0111i\u1ec3m 158 cm tr\u00ean tr\u1ee5c ho\u00e0nh.<\/p>\n\n\n\n
Ta th\u1eed x\u00e9t c\u00e1c tr\u01b0\u1eddng h\u1ee3p c\u00e1c \u00f4ng b\u1ed1 cao 182 cm tr\u1edf l\u00ean th\u00ec c\u00e1c \u0111\u1ee9a con \u0111\u1ea1i \u0111a s\u1ed1 ph\u00e2n b\u1ed1 \u1edf ph\u00eda d\u01b0\u1edbi \u0111\u01b0\u1eddng t\u1ea3n m\u1ea1n. Tr\u00e1i l\u1ea1i v\u1edbi c\u00e1c \u00f4ng b\u1ed1 c\u00f3 chi\u1ec1u cao th\u1ea5p h\u01a1n 166 cm th\u00ec nh\u1eefng \u0111\u1ee9a con th\u01b0\u1eddng c\u00f3 chi\u1ec1u cao ph\u00e2n b\u1ed1 ph\u00eda tr\u00ean \u0111\u01b0\u1eddng SD. Tr\u00ean h\u00ecnh v\u1ebd \u0111\u01b0\u1eddng th\u1eb3ng bi\u1ec3u di\u1ec5n b\u1eb1ng n\u00e9t \u0111\u1ee9t l\u00e0 \u0111\u01b0\u1eddng h\u1ed3i quy. D\u1ef1a v\u00e0o \u0111\u01b0\u1eddng h\u1ed3i quy c\u00f3 th\u1ec3 bi\u1ebft chi\u1ec1u cao b\u00ecnh qu\u00e2n c\u1ee7a nh\u1eefng \u0111\u1ee9a con so v\u1edbi chi\u1ec1u cao c\u1ee7a c\u00e1c \u00f4ng b\u1ed1. V\u00ed d\u1ee5 v\u1edbi c\u00e1c \u00f4ng b\u1ed1 cao 182 cm th\u00ec con cao trung b\u00ecnh 180 cm; c\u00f2n v\u1edbi c\u00e1c \u00f4ng b\u1ed1 cao 166 cm th\u00ec con cao b\u00ecnh qu\u00e2n 171 cm.<\/p>\n\n\n\n
Tr\u00ean \u0111\u00e2y ch\u00fang ta v\u1eeba x\u00e9t \u201chi\u1ec7u \u1ee9ng h\u1ed3i quy\u201d. C\u0103n c\u1ee9 hi\u1ec7u \u1ee9ng h\u1ed3i quy ch\u00fang ta c\u00f3 th\u1ec3 t\u00ecm khuynh h\u01b0\u1edbng chi\u1ec1u cao trung b\u00ecnh c\u1ee7a nh\u1eefng \u0111\u1ee9a con so v\u1edbi chi\u1ec1u cao trung b\u00ecnh c\u1ee7a c\u00e1c \u00f4ng b\u1ed1. V\u1edbi c\u00e1c \u00f4ng b\u1ed1 c\u00f3 chi\u1ec1u cao n\u00e0o \u0111\u00f3 th\u00ec chi\u1ec1u cao c\u1ee7a con c\u00f3 h\u01b0\u1edbng ng\u01b0\u1ee3c v\u1edbi \u0111\u01b0\u1eddng h\u1ed3i quy.<\/p>\n\n\n\n
Theo nh\u01b0 ph\u00e2n t\u00edch \u1edf tr\u00ean, cha m\u1eb9 cao to s\u1ebd sinh con c\u00f3 xu h\u01b0\u1edbng l\u00e0 con c\u00f3 t\u1ea7m v\u00f3c th\u1ea5p v\u00e0 ng\u01b0\u1ee3c l\u1ea1i khi cha m\u1eb9 l\u00f9n s\u1ebd sinh con cao to. Kh\u00f4ng ch\u1ec9 v\u1ec1 t\u00ednh tr\u1ea1ng chi\u1ec1u cao m\u00e0 nhi\u1ec1u lo\u1ea1i t\u00ednh tr\u1ea1ng di truy\u1ec1n \u1edf lo\u00e0i ng\u01b0\u1eddi c\u0169ng c\u00f3 xu h\u01b0\u1edbng h\u1ed3i quy, do c\u00f3 t\u00e1c d\u1ee5ng \u0111i\u1ec1u ti\u1ebft trong c\u00e1c di truy\u1ec1n t\u00ednh tr\u1ea1ng, m\u00e0 l\u00e0m cho c\u00e1c lo\u1ea1i t\u00ednh tr\u1ea1ng di truy\u1ec1n \u1edf lo\u00e0i ng\u01b0\u1eddi \u0111\u01b0\u1ee3c \u1ed5n \u0111\u1ecbnh qua nhi\u1ec1u th\u1ebf h\u1ec7.<\/p>\n\n\n\n
T\u1eeb kho\u00e1: \u0110\u01b0\u1eddng th\u1eb3ng h\u1ed3i quy; Hi\u1ec7u \u1ee9ng h\u1ed3i quy; \u0110\u1ed9 l\u1ec7ch<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
Th\u00f4ng th\u01b0\u1eddng khi \u0111i trong m\u01b0a ng\u01b0\u1eddi ta c\u1ed1 g\u1eafng ch\u1ea1y th\u1eadt nhanh v\u00ec cho r\u1eb1ng \u0111i c\u00e0ng nhanh th\u00ec c\u00e0ng \u00edt b\u1ecb \u01b0\u1edbt \u0111\u1eabm n\u01b0\u1edbc m\u01b0a. Th\u1ef1c t\u1ebf c\u00f3 ph\u1ea3i nh\u01b0 v\u1eady kh\u00f4ng? Gi\u1ea3 s\u1eed th\u00e2n ng\u01b0\u1eddi l\u00e0 m\u1ed9t c\u1ed9t vu\u00f4ng d\u00e0i th\u00ec, di\u1ec7n t\u00edch c\u1ee7a c\u00e1c m\u1eb7t tr\u01b0\u1edbc, m\u1eb7t b\u00ean v\u00e0 \u0111\u1ec9nh \u0111\u1ea7u […]<\/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":[15,9],"tags":[],"class_list":["post-7609","post","type-post","status-publish","format-standard","hentry","category-hoi-dap-khoa-hoc","category-toan-hoc"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7609","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=7609"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7609\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7609"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7609"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7609"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}