B\u1ea1n c\u00f3 bi\u1ebft ch\u1ed7 \u0111\u01b0\u1eddng s\u1eaft u\u1ed1n cong c\u00f3 d\u1ea1ng nh\u01b0 th\u1ebf n\u00e0o kh\u00f4ng? Khi chi\u1ebfc t\u00e0u cao t\u1ed1c t\u1eeb \u0111o\u1ea1n \u0111\u01b0\u1eddng th\u1eb3ng \u0111i v\u00e0o \u0111o\u1ea1n \u0111\u01b0\u1eddng cong, \u0111\u01b0\u1eddng s\u1eaft ph\u1ea3i nh\u01b0 th\u1ebf n\u00e0o \u0111\u1ec3 khi t\u00e0u \u0111\u1ed5i h\u01b0\u1edbng m\u00e0 kh\u00f4ng g\u00e2y l\u00ean s\u1ef1 c\u1ed1? C\u00e2u tr\u1ea3 l\u1eddi l\u00e0 ph\u1ea3i c\u00f3 \u0111o\u1ea1n \u0111\u01b0\u1eddng trung gian \u0111\u1ec3 gi\u1ea3m b\u1edbt ch\u1ea5n \u0111\u1ed9ng. \u1ede nhi\u1ec1u n\u01b0\u1edbc, ng\u01b0\u1eddi ta d\u00f9ng \u0111o\u1ea1n \u0111\u01b0\u1eddng trung gian n\u00e0y c\u00f3 d\u1ea1ng m\u1ed9t \u0111\u01b0\u1eddng parabon d\u1ea1ng y = kx3(k l\u00e0 h\u1eb1ng s\u1ed1) l\u00e0 \u0111o\u1ea1n cung sau \u0111\u00f3 \u0111\u1ebfn \u0111o\u1ea1n cung tr\u00f2n.<\/p>\n\n\n\n
V\u00ec sao ng\u01b0\u1eddi ta l\u1ea1i d\u00f9ng lo\u1ea1i parabon b\u1eadc ba y = kx3 l\u00e0m \u0111o\u1ea1n trung gian? \u0110\u00f3 l\u00e0 \u0111\u1eb7c \u0111i\u1ec3m v\u1ec1 \u0111\u1ed9 cong c\u1ee7a c\u00e1c lo\u1ea1i \u0111\u01b0\u1eddng cong. Th\u1ebf n\u00e0o l\u00e0 \u0111\u1ed9 cong c\u1ee7a c\u00e1c \u0111\u01b0\u1eddng cong? Nh\u01b0 \u1edf h\u00ecnh v\u1ebd hai \u0111o\u1ea1n \u0111\u01b0\u1eddng cong C1 v\u00e0 C2 c\u00f3 c\u00f9ng \u0111\u1ed9 d\u00e0i l\u00e0 A1B1 v\u00e0 A2B2, r\u00f5 r\u00e0ng l\u00e0 \u0111\u1ed9 cong \u1edf A1B1 l\u1edbn h\u01a1n \u1edf A2B2 nhi\u1ec1u.<\/p>\n\n\n\n
Ta v\u1ebd hai ti\u1ebfp tuy\u1ebfn t\u1ea1i c\u00e1c \u0111i\u1ec3m \u0111\u1ea7u v\u00e0 cu\u1ed1i c\u1ee7a c\u00e1c \u0111\u01b0\u1eddng cong. C\u00e1c ti\u1ebfp tuy\u1ebfn t\u1ea1i c\u00e1c \u0111i\u1ec3m \u0111\u1ea7u v\u00e0 cu\u1ed1i c\u1ee7a c\u00e1c \u0111\u01b0\u1eddng cong t\u1ea1o th\u00e0nh c\u00e1c g\u00f3c \u03b11 v\u00e0 \u03b12 t\u01b0\u01a1ng \u1ee9ng. R\u00f5 r\u00e0ng l\u00e0 \u03b11 > \u03b12 c\u00f3 ngh\u0129a l\u00e0, n\u1ebfu \u0111\u1ed9 cong c\u1ee7a \u0111\u01b0\u1eddng cong c\u00e0ng l\u1edbn th\u00ec g\u00f3c c\u1ee7a c\u00e1c ti\u1ebfp tuy\u1ebfn \u1edf \u0111i\u1ec3m \u0111\u1ea7u v\u00e0 \u0111i\u1ec3m cu\u1ed1i c\u1ee7a c\u00e1c \u0111\u01b0\u1eddng cong c\u00e0ng l\u1edbn. V\u1eady ta c\u00f3 th\u1ec3 d\u00f9ng g\u00f3c c\u1ee7a c\u00e1c ti\u1ebfp tuy\u1ebfn t\u1ea1i \u0111i\u1ec3m \u0111\u1ea7u v\u00e0 \u0111i\u1ec3m cu\u1ed1i c\u1ee7a \u0111\u01b0\u1eddng cong \u0111\u1ec3 \u0111o \u0111\u1ed9 cong.<\/p>\n\n\n\n
V\u00ed d\u1ee5 v\u1edbi c\u00e1c \u0111\u01b0\u1eddng th\u1eb3ng th\u00ec \u0111\u01b0\u1eddng ti\u1ebfp tuy\u1ebfn t\u1ea1i c\u00e1c m\u00fat c\u1ee7a \u0111\u01b0\u1eddng th\u1eb3ng \u0111\u1ec1u tr\u00f9ng nhau n\u00ean g\u00f3c c\u00e1c ti\u1ebfp tuy\u1ebfn b\u1eb1ng 0, n\u00ean \u0111\u1ed9 cong c\u1ee7a \u0111\u01b0\u1eddng th\u1eb3ng b\u1eb1ng 0.<\/p>\n\n\n\n
V\u1edbi \u0111\u01b0\u1eddng tr\u00f2n b\u00e1n k\u00ednh R, ti\u1ebfp tuy\u1ebfn t\u1ea1i hai m\u00fat c\u1ee7a cung tr\u00f2n b\u1eb1ng v\u1edbi g\u00f3c \u03b1 c\u1ee7a hai b\u00e1n k\u00ednh OP v\u00e0 OQ. N\u1ebfu \u03b1 \u0111o b\u1eb1ng \u0111\u01a1n v\u1ecb ra\u0111ian th\u00ec = R\u03b1 n\u00ean \u0111\u1ed9 cong c\u1ee7a cung l\u00e0: .<\/p>\n\n\n\n
Nh\u01b0 v\u1eady v\u1edbi \u0111\u01b0\u1eddng tr\u00f2n th\u00ec \u0111\u1ed9 cong t\u1ea1i m\u1ecdi \u0111i\u1ec3m l\u00e0 1\/R.<\/p>\n\n\n\n
Khi ta d\u00f9ng \u0111\u01b0\u1eddng cong b\u1eadc ba: y = kx3 t\u1eeb 0 \u0111\u1ebfn B \u0111\u1ec3 n\u1ed1i \u0111o\u1ea1n th\u1eb3ng v\u1edbi cung tr\u00f2n t\u1ee9c cho \u0111\u1ed9 cong c\u1ee7a \u0111\u01b0\u1eddng s\u1eaft thay \u0111\u1ed5i t\u1eeb 0 \u0111\u1ebfn 1\/R, kh\u00f4ng l\u00e0m \u0111\u1ed9 cong c\u1ee7a \u0111\u01b0\u1eddng s\u1eaft thay \u0111\u1ed5i \u0111\u1ed9t ng\u1ed9t n\u00ean kh\u00f4ng g\u00e2y ra s\u1ef1 c\u1ed1.<\/p>\n\n\n\n
T\u1eeb kho\u00e1: \u0110o\u1ea1n \u0111\u01b0\u1eddng s\u1eaft ti\u1ebfp n\u1ed1i th\u1eb3ng; \u0110\u1ed9 cong; \u0110\u01b0\u1eddng cong Parabon b\u1eadc ba.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
B\u1ea1n c\u00f3 bi\u1ebft ch\u1ed7 \u0111\u01b0\u1eddng s\u1eaft u\u1ed1n cong c\u00f3 d\u1ea1ng nh\u01b0 th\u1ebf n\u00e0o kh\u00f4ng? Khi chi\u1ebfc t\u00e0u cao t\u1ed1c t\u1eeb \u0111o\u1ea1n \u0111\u01b0\u1eddng th\u1eb3ng \u0111i v\u00e0o \u0111o\u1ea1n \u0111\u01b0\u1eddng cong, \u0111\u01b0\u1eddng s\u1eaft ph\u1ea3i nh\u01b0 th\u1ebf n\u00e0o \u0111\u1ec3 khi t\u00e0u \u0111\u1ed5i h\u01b0\u1edbng m\u00e0 kh\u00f4ng g\u00e2y l\u00ean s\u1ef1 c\u1ed1? C\u00e2u tr\u1ea3 l\u1eddi l\u00e0 ph\u1ea3i c\u00f3 \u0111o\u1ea1n \u0111\u01b0\u1eddng trung gian […]<\/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-7607","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\/7607","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=7607"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7607\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7607"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7607"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7607"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}