Xin c\u00e1c b\u1ea1n h\u00e3y \u0111\u1ed5 v\u00e0o m\u1ed9t th\u00f9ng \u0111\u1ef1ng h\u00ecnh l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt m\u1ed9t l\u01b0\u1ee3ng n\u01b0\u1edbc c\u00f3 m\u00e0u (\u0111\u1ec3 d\u1ec5 nh\u00ecn th\u1ea5y), h\u00e3y c\u1ed1 \u0111\u1ecbnh th\u00f9ng l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt theo m\u1ed9t c\u1ea1nh \u0111\u00e1y. Nghi\u00eang t\u1eeb t\u1eeb th\u00f9ng n\u01b0\u1edbc nh\u01b0ng gi\u1eef kh\u00f4ng cho n\u01b0\u1edbc \u0111\u1ed5 ra ngo\u00e0i. Tu\u1ef3 theo \u0111\u1ed9 nghi\u00eang c\u1ee7a th\u00f9ng, b\u1ea1n s\u1ebd th\u1ea5y kh\u1ed1i n\u01b0\u1edbc trong th\u00f9ng c\u00f3 nhi\u1ec1u h\u00ecnh d\u1ea1ng kh\u00e1c nhau. B\u1ea1n h\u00e3y quan s\u00e1t k\u0129 xem h\u00ecnh d\u1ea1ng kh\u1ed1i n\u01b0\u1edbc thay \u0111\u1ed5i theo quy lu\u1eadt n\u00e0o?<\/p>\n\n\n\n
Tr\u01b0\u1edbc h\u1ebft ta \u0111\u1ec3 th\u00f9ng \u0111\u1ee9ng th\u1eb3ng tr\u00ean m\u1eb7t b\u00e0n theo m\u1eb7t \u0111\u00e1y ABCD nh\u01b0 \u1edf h\u00ecnh 1. B\u1ea5y gi\u1edd m\u1eb7t b\u00ean s\u1ebd c\u00f3 d\u1ea1ng m\u1ed9t h\u00ecnh ch\u1eef nh\u1eadt BCFE. Th\u1ec3 t\u00edch c\u1ee7a kh\u1ed1i n\u01b0\u1edbc s\u1ebd b\u1eb1ng di\u1ec7n t\u00edch m\u1eb7t \u0111\u00e1y BCFE nh\u00e2n v\u1edbi chi\u1ec1u cao CD.<\/p>\n\n\n\n
Ti\u1ebfp theo ta c\u1ed1 \u0111\u1ecbnh th\u00f9ng v\u00e0 gi\u1eef \u0111\u00e1y ABCD theo c\u1ea1nh CD. Nghi\u00eang th\u00f9ng t\u1eeb t\u1eeb theo nh\u01b0 v\u1ecb tr\u00ed cho \u1edf h\u00ecnh v\u1ebd b\u00ean d\u01b0\u1edbi. B\u1ea5y gi\u1edd di\u1ec7n t\u00edch m\u1eb7t b\u00ean BCFE s\u1ebd l\u00e0 h\u00ecnh thang. H\u00ecnh thang n\u00e0y c\u00f3 m\u1ed9t c\u1ea1nh \u0111\u00e1y BE = a v\u00e0 m\u1ed9t c\u1ea1nh \u0111\u00e1y l\u00e0 CF = b v\u00e0 a + b s\u1ebd l\u00e0 m\u1ed9t s\u1ed1 kh\u00f4ng \u0111\u1ed5i. B\u00e2y gi\u1edd ti\u1ebfp t\u1ee5c cho th\u00f9ng nghi\u00eang h\u01a1n n\u1eefa, nh\u01b0ng v\u1eabn gi\u1eef m\u1eb7t b\u00ean c\u00f3 d\u1ea1ng h\u00ecnh thang th\u00ec t\u1ed5ng s\u1ed1 a + b v\u1eabn kh\u00f4ng thay \u0111\u1ed5i. \u0110\u1ed3ng th\u1eddi khi a gi\u1ea3m bao nhi\u00eau \u0111\u1ed9 d\u00e0i th\u00ec b t\u0103ng \u0111\u1ed9 d\u00e0i b\u1ea5y nhi\u00eau. B\u1ea1n c\u00f3 bi\u1ebft t\u1ea1i sao kh\u00f4ng?<\/p>\n\n\n\n
Kh\u1ed1i n\u01b0\u1edbc v\u1eabn l\u1ea5y BCFE l\u00e0m \u0111\u00e1y v\u00e0 CD l\u00e0m chi\u1ec1u cao c\u1ee7a h\u00ecnh l\u0103ng tr\u1ee5 t\u1ee9 gi\u00e1c v\u00e0 th\u1ec3 t\u00edch kh\u1ed1i n\u01b0\u1edbc s\u1ebd l\u00e0 t\u00edch s\u1ed1 c\u1ee7a di\u1ec7n t\u00edch \u0111\u00e1y nh\u00e2n v\u1edbi chi\u1ec1u cao CD. Do di\u1ec7n t\u00edch h\u00ecnh thang kh\u00f4ng thay \u0111\u1ed5i, chi\u1ec1u cao CD c\u0169ng kh\u00f4ng thay \u0111\u1ed5i, c\u0169ng l\u00e0 th\u1ec3 t\u00edch n\u01b0\u1edbc nh\u01b0 \u1edf h\u00ecnh tr\u00ean.<\/p>\n\n\n\n
N\u1ebfu ti\u1ebfp t\u1ee5c l\u00e0m nghi\u00eang th\u00f9ng th\u00ec m\u1eb7t b\u00ean s\u1ebd c\u00f3 d\u1ea1ng h\u00ecnh tam gi\u00e1c ECF. Th\u1ec3 t\u00edch kh\u1ed1i n\u01b0\u1edbc s\u1ebd l\u00e0 h\u00ecnh l\u0103ng tr\u1ee5 \u0111\u00e1y tam gi\u00e1c ECF v\u00e0 chi\u1ec1u cao CD. Th\u1ec3 t\u00edch kh\u1ed1i n\u01b0\u1edbc v\u1eabn l\u00e0 th\u1ec3 t\u00edch kh\u1ed1i l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt \u0111\u00e1y ch\u1eef nh\u1eadt BCFE ho\u1eb7c \u0111\u00e1y h\u00ecnh thang BCFE. Gi\u1ea3 s\u1eed CE = c, CF = b, di\u1ec7n t\u00edch h\u00ecnh tam gi\u00e1c ECF l\u00e0 1\/2b x c v\u00e0 b x c l\u00e0 kh\u00f4ng thay \u0111\u1ed5i.<\/p>\n\n\n\n
Khi nghi\u00eang th\u00f9ng th\u00ec kh\u1ed1i n\u01b0\u1edbc thay \u0111\u1ed5i t\u1eeb kh\u1ed1i l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt, \u0111\u1ebfn l\u0103ng tr\u1ee5 \u0111\u00e1y h\u00ecnh thang, r\u1ed3i \u0111\u1ebfn l\u0103ng tr\u1ee5 \u0111\u00e1y tam gi\u00e1c, nh\u01b0ng n\u1ebfu kh\u00f4ng \u0111\u1ec3 n\u01b0\u1edbc ch\u1ea3y ra ngo\u00e0i th\u00ec th\u1ec3 t\u00edch n\u01b0\u1edbc v\u1eabn kh\u00f4ng thay \u0111\u1ed5i cho d\u00f9 h\u00ecnh d\u00e1ng kh\u1ed1i n\u01b0\u1edbc c\u00f3 thay \u0111\u1ed5i (xem h\u00ecnh 1, 2, 3).<\/p>\n\n\n\n
V\u00ec sao th\u00f9ng \u0111\u1ef1ng d\u1ea7u, ph\u00edch \u0111\u1ef1ng n\u01b0\u1edbc n\u00f3ng \u0111\u1ec1u c\u00f3 d\u1ea1ng h\u00ecnh tr\u1ee5?<\/p>\n\n\n\n
Th\u00f9ng d\u1ea7u, ph\u00edch n\u01b0\u1edbc \u0111\u1ec1u l\u00e0 c\u00e1c th\u00f9ng, b\u00ecnh \u0111\u1ef1ng ch\u1ea5t l\u1ecfng.<\/p>\n\n\n\n
B\u1ea1n c\u00f3 ch\u00fa \u00fd c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng ch\u1ea5t l\u1ecfng \u0111\u1ec1u c\u00f3 d\u1ea1ng h\u00ecnh tr\u1ee5, \u0111i\u1ec1u n\u00e0y c\u00f3 li\u00ean quan g\u00ec \u0111\u1ebfn to\u00e1n h\u1ecdc kh\u00f4ng?<\/p>\n\n\n\n
Khi s\u1ea3n xu\u1ea5t c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng ng\u01b0\u1eddi ta th\u01b0\u1eddng ch\u00fa \u00fd \u0111\u1ebfn vi\u1ec7c ti\u1ebft ki\u1ec7m v\u1eadt li\u1ec7u: V\u1edbi c\u00f9ng m\u1ed9t l\u01b0\u1ee3ng v\u1eadt li\u1ec7u l\u00e0m th\u1ebf n\u00e0o s\u1ea3n xu\u1ea5t \u0111\u01b0\u1ee3c b\u00ecnh \u0111\u1ef1ng ch\u1ea5t l\u1ecfng v\u1edbi dung t\u00edch l\u1edbn nh\u1ea5t.<\/p>\n\n\n\n
Ta \u0111\u00e3 bi\u1ebft trong h\u00ecnh h\u1ecdc ph\u1eb3ng, trong c\u00e1c h\u00ecnh \u0111a gi\u00e1c \u0111\u1ec1u v\u00e0 h\u00ecnh tr\u00f2n c\u00f3 c\u00f9ng chu vi th\u00ec h\u00ecnh tr\u00f2n c\u00f3 di\u1ec7n t\u00edch l\u1edbn nh\u1ea5t. V\u00ed d\u1ee5 v\u1edbi di\u1ec7n t\u00edch 100 mm2 th\u00ec h\u00ecnh vu\u00f4ng c\u00f3 chu vi 40 mm, h\u00ecnh tam gi\u00e1c \u0111\u1ec1u chu vi 45,6 mm. Nh\u01b0 v\u1eady v\u1edbi c\u00f9ng m\u1ed9t di\u1ec7n t\u00edch th\u00ec tam gi\u00e1c \u0111\u1ec1u c\u00f3 chu vi l\u1edbn nh\u1ea5t, h\u00ecnh vu\u00f4ng cho chu vi b\u00e9 h\u01a1n v\u00e0 h\u00ecnh tr\u00f2n c\u00f3 chu vi b\u00e9 nh\u1ea5t. V\u00ec v\u1eady v\u1edbi c\u00e1c d\u1ee5ng c\u1ee5 \u0111\u1ef1ng ch\u1ea5t l\u1ecfng, n\u1ebfu c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng c\u00f3 c\u00f9ng chi\u1ec1u cao th\u00ec l\u0103ng tr\u1ee5 tr\u00f2n c\u00f3 dung t\u00edch l\u1edbn nh\u1ea5t, v\u00e0 vi\u1ec7c s\u1ea3n xu\u1ea5t c\u00e1c l\u0103ng tr\u1ee5 tr\u00f2n s\u1ebd t\u1ed1n \u00edt nguy\u00ean li\u1ec7u nh\u1ea5t. Do v\u1eady c\u00e1c th\u00f9ng \u0111\u1ef1ng d\u1ea7u, ph\u00edch n\u01b0\u1edbc l\u00e0 nh\u1eefng \u0111\u1ed3 \u0111\u1ef1ng ch\u1ea5t l\u1ecfng th\u01b0\u1eddng c\u00f3 d\u1ea1ng l\u0103ng tr\u1ee5 tr\u00f2n.<\/p>\n\n\n\n
Th\u1ebf c\u00f3 lo\u1ea1i b\u00ecnh \u0111\u1ef1ng d\u1ea1ng n\u00e0o ti\u1ebft ki\u1ec7m nguy\u00ean v\u1eadt li\u1ec7u h\u01a1n l\u0103ng tr\u1ee5 tr\u00f2n kh\u00f4ng? C\u00f3. \u0110\u00f3 ch\u00ednh l\u00e0 h\u00ecnh c\u1ea7u. V\u1edbi c\u00f9ng m\u1ed9t l\u01b0\u1ee3ng v\u1eadt li\u1ec7u th\u00ec \u0111\u1ed3 \u0111\u1ef1ng h\u00ecnh c\u1ea7u s\u1ea3n xu\u1ea5t ra s\u1ebd c\u00f3 dung t\u00edch l\u1edbn nh\u1ea5t. N\u00f3i c\u00e1ch kh\u00e1c s\u1ea3n xu\u1ea5t c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng ch\u1ea5t l\u1ecfng h\u00ecnh c\u1ea7u ti\u1ebft ki\u1ec7m \u0111\u01b0\u1ee3c v\u1eadt li\u1ec7u nhi\u1ec1u nh\u1ea5t. Tuy nhi\u00ean, do c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng h\u00ecnh c\u1ea7u d\u1ec5 b\u1ecb l\u0103n \u0111i, l\u0103n l\u1ea1i, kh\u00f3 \u0111\u1ee9ng y\u00ean; vi\u1ec7c s\u1ea3n xu\u1ea5t c\u00e1c v\u1eadt d\u1ee5ng h\u00ecnh c\u1ea7u c\u0169ng kh\u00f3 h\u01a1n, kh\u00f3 \u0111\u1eady n\u1eafp h\u01a1n n\u00ean b\u00ecnh h\u00ecnh c\u1ea7u kh\u00f4ng c\u00f3 \u00fd ngh\u0129a th\u1ef1c t\u1ebf.<\/p>\n\n\n\n
Tuy nhi\u00ean c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng v\u1eadt r\u1eafn nh\u01b0 h\u00f2m, r\u01b0\u01a1ng sao l\u1ea1i kh\u00f4ng s\u1ea3n xu\u1ea5t c\u00f3 d\u1ea1ng h\u00ecnh tr\u1ee5? Cho d\u00f9 c\u00e1c \u0111\u1ed3 \u0111\u1ef1ng h\u00ecnh tr\u1ee5 ti\u1ebft ki\u1ec7m \u0111\u01b0\u1ee3c nguy\u00ean v\u1eadt li\u1ec7u nh\u01b0ng \u0111\u1ef1ng c\u00e1c v\u1eadt r\u1eafn l\u1ea1i kh\u00f4ng thu\u1eadn ti\u1ec7n l\u1eafm n\u00ean ng\u01b0\u1eddi ta th\u01b0\u1eddng s\u1ea3n xu\u1ea5t ch\u00fang \u1edf d\u1ea1ng kh\u1ed1i l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt.<\/p>\n\n\n\n
T\u1eeb kho\u00e1: L\u0103ng tr\u1ee5 tr\u00f2n; H\u00ecnh c\u1ea7u.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
Xin c\u00e1c b\u1ea1n h\u00e3y \u0111\u1ed5 v\u00e0o m\u1ed9t th\u00f9ng \u0111\u1ef1ng h\u00ecnh l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt m\u1ed9t l\u01b0\u1ee3ng n\u01b0\u1edbc c\u00f3 m\u00e0u (\u0111\u1ec3 d\u1ec5 nh\u00ecn th\u1ea5y), h\u00e3y c\u1ed1 \u0111\u1ecbnh th\u00f9ng l\u0103ng tr\u1ee5 ch\u1eef nh\u1eadt theo m\u1ed9t c\u1ea1nh \u0111\u00e1y. Nghi\u00eang t\u1eeb t\u1eeb th\u00f9ng n\u01b0\u1edbc nh\u01b0ng gi\u1eef kh\u00f4ng cho n\u01b0\u1edbc \u0111\u1ed5 ra ngo\u00e0i. Tu\u1ef3 theo \u0111\u1ed9 nghi\u00eang c\u1ee7a th\u00f9ng, b\u1ea1n […]<\/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-7555","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\/7555","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=7555"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/7555\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=7555"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=7555"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=7555"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}