maths~maths~
2011-04-20 3:04 am
圖片參考：http://imgcld.yimg.com/8/n/HA00510450/o/701104190091313873428770.jpg
A rectangle wall ABCD with dimensions 10m × 6m stands vertically on the horizontal ground along the east-west direction. When the sun shines from N25°W with an angle of elevation 18° from B',the shadow of the wall on the ground is BB'C'C.
Find the angle of elevation of A from C'. ans:13.8°
回答 (1)
2011-04-20 7:21 am
✔ 最佳答案
ㄥBCC' = ㄥWBB' = 90+25 = 115°DC / CC' = tan18°
CC' = DC / tan18° = 6 / tan18°
BC' ² = BC² + CC' ² - 2 BC CC' cos ㄥBCC'
BC' ² = 10² + (6/tan18°)² - 2 * 10 * 6/tan18° cos115°
BC' = 24.4352
Let x be the angle of elevation of A from C' :
tan x = AB/BC'
tan x = 6 / 24.4352
x = 13.8°
收錄日期: 2021-04-21 22:21:06
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110419000051KK00913