H\u00ecnh thoi l\u00e0 m\u1ed9t trong nh\u1eefng d\u1ea1ng h\u00ecnh \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nhi\u1ec1u trong c\u00e1c b\u00e0i gi\u1ea3i to\u00e1n h\u1ecdc. \u0110\u1ec3 gi\u1ea3i \u0111\u01b0\u1ee3c c\u00e1c b\u00e0i to\u00e1n t\u00ednh di\u1ec7n t\u00edch th\u00ec c\u00e1c ban c\u1ea7n ph\u1ea3i n\u1eafm v\u1eefng c\u00e1c c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch tr\u01b0\u1edbc. H\u00e3y c\u00f9ng tham kh\u1ea3o c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00ednh h\u00ecnh thoi d\u01b0\u1edbi \u0111\u00e2y nh\u00e9.<\/p>\n

T\u1ed5ng h\u1ee3p c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh thoi<\/h2>\n

H\u00ecnh thoi l\u00e0 h\u00ecnh t\u1ee9 gi\u00e1c c\u00f3 4 c\u1ea1nh b\u1eb1ng nhau v\u00e0 c\u00f3 m\u1ed9t s\u1ed1 t\u00ednh ch\u1ea5t c\u01a1 b\u1ea3n nh\u01b0: 2 g\u00f3c \u0111\u1ed1i b\u1eb1ng nhau,\u0111\u01b0\u1eddng ch\u00e9o vu\u00f4ng g\u00f3c t\u1ea1i trung \u0111i\u1ec3m c\u1ee7a m\u1ed7i \u0111\u01b0\u1eddng v\u00e0 \u0111\u1ed3ng th\u1eddi l\u00e0 \u0111\u01b0\u1eddng ph\u00e2n gi\u00e1c c\u1ee7a g\u00f3c.
\nT\u00ednh ch\u1ea5t c\u1ee7a h\u00ecnh thoi<\/strong><\/p>\n

<\/p>\n

H\u00ecnh thoi c\u00f3 t\u1ea5t c\u1ea3 c\u00e1c t\u00ednh ch\u1ea5t c\u1ee7a h\u00ecnh b\u00ecnh h\u00e0nh:
\n\u0110\u00f3 l\u00e0 c\u00e1c c\u1ea1nh \u0111\u1ed1i song song v\u00e0 b\u1eb1ng bang nhau
\nC\u00e1c g\u00f3c \u0111\u1ed1i b\u1eb1ng nhau
\nHai \u0111\u01b0\u1eddng ch\u00e9o c\u1eaft nhau t\u1ea1i trung \u0111i\u1ec3m c\u1ee7a m\u1ed7i \u0111\u01b0\u1eddng
\nV\u00e0 n\u00f3 c\u00f2n c\u00f2n c\u00f3 t\u00ednh ch\u1ea5t ri\u00eang nh\u01b0 hai \u0111\u01b0\u1eddng ch\u00e9o vu\u00f4ng g\u00f3c v\u1edbi nhai, hai \u0111\u01b0\u1eddng ch\u00e9p l\u00e0 \u0111\u01b0\u1eddng ph\u00e2n gi\u00e1c c\u1ee7a c\u00e1c g\u00f3c h\u00ecnh thoi.
\nD\u1ea5u hi\u1ec7u nh\u1eadn bi\u1ebft c\u1ee7a h\u00ecnh thoi
\nH\u00ecnh thoi l\u00e0 t\u1ee9 gi\u00e1c c\u00f3 b\u1ed1n c\u1ea1nh b\u1eb1ng nhau b\u1eb1ng nhau l\u00e0 h\u00ecnh thoi. H\u00ecnh b\u00ecnh h\u00e0nh c\u00f3 hai \u0111\u01b0\u1eddng ch\u00e9o vu\u00f4ng g\u00f3c v\u1edbi nhau c\u0169ng \u0111\u01b0\u1ee3c xem l\u00e0 h\u00ecnh thoi l\u00e0 h\u00ecnh thoi. H\u00ecnh b\u00ecnh h\u00e0nh c\u00f3 m\u1ed9t \u0111\u01b0\u1eddng ch\u00e9o l\u00e0 \u0111\u01b0\u1eddng ph\u00e2n gi\u00e1c c\u1ee7a m\u1ed9t g\u00f3c h\u00ecnh thoi.
\nC\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ednh thoi:
\nC\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh thoi b\u1eb1ng n\u1eeda t\u00edch c\u1ee7a hai \u0111\u01b0\u1eddng ch\u00e9o.
\nS= 1\/2(d1xd2)
\nTrong \u0111\u00f3 D1 v\u00e0 D2 l\u1ea7n l\u01b0\u1ee3t l\u00e0 2 \u0111\u01b0\u1eddng ch\u00e9o c\u1ee7a h\u00ecnh thoi.<\/p>\n

B\u00e0i t\u1eadp \u00e1p d\u1ee5ng c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch h\u00ecnh thoi<\/strong><\/h3>\n

Di\u1ec7n t\u00edch h\u00ecnh thoi b\u1eb1ng t\u00edch c\u1ee7a \u0111\u1ed9 d\u00e0i hai \u0111\u01b0\u1eddng ch\u00e9o chia cho 2 (c\u00f9ng m\u1ed9t \u0111\u01a1n v\u1ecb \u0111o di\u1ec7n t\u00edch)
\nS = (m x n) : 2
\nTrong \u0111\u00f3, S l\u00e0 di\u1ec7n t\u00edch c\u1ee7a h\u00ecnh thoi; m, n l\u00e0 \u0111\u1ed9 d\u00e0i c\u1ee7a hai \u0111\u01b0\u1eddng ch\u00e9o.
\nB\u00c0I 1.
\nT\u00ednh di\u1ec7n t\u00edch c\u1ee7a
\na) H\u00ecnh thoi ABCD, bi\u1ebft:
\nAC = 3cm
\nBD = 4cm
\nb) H\u00ecnh thoi MNPQ bi\u1ebft:
\nMN = 7cm
\nNQ = 4cm
\n\u0110\u00e1p \u00e1n:
\na) Di\u1ec7n t\u00edch h\u00ecnh thoi ABCD l\u00e0: (3 x 5) : 2 = 15\/2 (cm2)
\nb) Di\u1ec7n t\u00edch h\u00ecnh thoi MNPQ l\u00e0: (7 x 4) : 2 = 14 (cm2)
\nB\u00c0I 2. (
\nT\u00ednh di\u1ec7n t\u00edch h\u00ecnh thoi, bi\u1ebft:
\na) \u0110\u1ed9 d\u00e0i c\u00e1c \u0111\u01b0\u1eddng ch\u00e9o l\u00e0 5dm v\u00e0 20dm;
\nb) \u0110\u1ed9 d\u00e0i c\u00e1c \u0111\u01b0\u1eddng ch\u00e9o l\u00e0 4m v\u00e0 15dm.
\n\u0110\u00e1p \u00e1n:
\na) Di\u1ec7n t\u00edch h\u00ecnh thoi l\u00e0: (5 x 20) : 2 = 50 (dm2)
\nb) \u0110\u1ed5i 4m = 40dm
\nDi\u1ec7n t\u00edch h\u00ecnh thoi l\u00e0: (40 x 15) : 2 = 300 (dm2)
\nB\u00c0I 3.
\n\u0110\u00fang ghi \u0110, sai ghi S:<\/p>\n

a) Di\u1ec7n t\u00edch h\u00ecnh thoi b\u1eb1ng di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt
\nb) Di\u1ec7n t\u00edch h\u00ecnh thoi b\u1eb1ng 1\/2 di\u1ec7n t\u00edch h\u00ecnh ch\u1eef nh\u1eadt
\n\u0110\u00e1p \u00e1n:
\na) Ghi S
\nb) Ghi \u0110<\/p>\n

H\u00e3y c\u00f9ng \u00e1p d\u1ee5ng c\u00e1c c\u00f4ng th\u1ee9c t\u00ednh di\u1ec7n t\u00edch H\u00ecnh Thoi tr\u00ean \u0111\u1ec3 l\u00e0m b\u00e0i t\u1eadp nh\u00e9, ch\u00fac c\u00e1c b\u1ea1n th\u00e0nh c\u00f4ng.<\/p>\n","protected":false},"excerpt":{"rendered":"

H\u00ecnh thoi l\u00e0 m\u1ed9t trong nh\u1eefng d\u1ea1ng h\u00ecnh \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng nhi\u1ec1u trong c\u00e1c b\u00e0i gi\u1ea3i to\u00e1n h\u1ecdc. \u0110\u1ec3 gi\u1ea3i \u0111\u01b0\u1ee3c c\u00e1c b\u00e0i to\u00e1n t\u00ednh di\u1ec7n t\u00edch th\u00ec c\u00e1c ban… <\/p>\n","protected":false},"author":9,"featured_media":9996,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[413,406],"tags":[],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/posts\/9994"}],"collection":[{"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/comments?post=9994"}],"version-history":[{"count":0,"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/posts\/9994\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/media\/9996"}],"wp:attachment":[{"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/media?parent=9994"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/categories?post=9994"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/onthitot.com\/wp-json\/wp\/v2\/tags?post=9994"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}