BC = 21 cm, angle ABC = 63 degree and angle DCB = 47 degree. Find AB.
Figure: [img]http://img199.imageshack.us/img199/9164/79436181.jpg[/img]
更新1:
http://img199.imageshack.us/img199/9164/79436181.jpg
F4 Maths sine law ( -_-) zzZ
2010-03-03 6:57 am
In the figure, ABCD is a trapezium with AD // BC, AD = 10 cm,
BC = 21 cm, angle ABC = 63 degree and angle DCB = 47 degree. Find AB.
Figure: [img]http://img199.imageshack.us/img199/9164/79436181.jpg[/img]
BC = 21 cm, angle ABC = 63 degree and angle DCB = 47 degree. Find AB.
Figure: [img]http://img199.imageshack.us/img199/9164/79436181.jpg[/img]
回答 (2)
2010-03-03 7:23 am
✔ 最佳答案
add DX, so DX//AB, DX=AB, ADBX is an //gramXC=21-10cm=11cm
angle dxc=180-63-47=70(angle sum of tri.)
(sin 70)/11 = (sin 47)/dx 9(sin formula)
ab=dx=8.561193884...cm
圖片參考：http://imgcld.yimg.com/8/n/HA00195895/o/701003020179013873415320.jpg
記得補番d degree符號呀-v-"
2010-03-03 7:53 am
Method 1 : Using sine law
http://i320.photobucket.com/albums/nn347/old-master/100302_2a.jpg?t=1267544916
圖片參考：http://i320.photobucket.com/albums/nn347/old-master/100302_2a.jpg?t=1267544916
Method 2 : Using right-angled triangles
http://i320.photobucket.com/albums/nn347/old-master/100302_2b.jpg?t=1267544874
圖片參考：http://i320.photobucket.com/albums/nn347/old-master/100302_2b.jpg?t=1267544874
http://i320.photobucket.com/albums/nn347/old-master/100302_2a.jpg?t=1267544916
圖片參考：http://i320.photobucket.com/albums/nn347/old-master/100302_2a.jpg?t=1267544916
Method 2 : Using right-angled triangles
http://i320.photobucket.com/albums/nn347/old-master/100302_2b.jpg?t=1267544874
圖片參考：http://i320.photobucket.com/albums/nn347/old-master/100302_2b.jpg?t=1267544874
參考: 老爺子
收錄日期: 2021-05-01 01:01:30
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100302000051KK01790