F.3 maths Trigonmetry2
2009-08-07 2:19 am
圖片參考：http://img22.imageshack.us/img22/2275/16398264.jpg
In the figure, an advertising signboard DC is attached on a vertical wall and it is 8 m above the groung.
A is a point 18m away from the foot of the wall B, where A and B are on the same horizontal ground.
If the angles of elevation of the top and the bottom of the signboard from A differ by 10 , find the height of the signboard DC.
回答 (2)
2009-08-07 2:28 am
✔ 最佳答案
tanㄥCAB = 8/18
ㄥCAB = 23.9624889...
So ㄥDAB = 23.9624889...+ 10 = 33.9624889...
So (DC + 8) / 18 = tan 33.9624889...
DC = 4.124m(3 dec.)
2009-08-07 2:33 am
tan/CAB=8/18
/CAB=23.96248897
tan/DAB=DB/18
tan33.96248897=DB/18
DB=12.124106301
So DC=DB-8
=4.124106301m
/CAB=23.96248897
tan/DAB=DB/18
tan33.96248897=DB/18
DB=12.124106301
So DC=DB-8
=4.124106301m
參考: Myself
收錄日期: 2021-04-21 22:03:18
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090806000051KK01917