maths F.3 --urgent

乜點都無好難計
設helicopter既位置叫 A helicopter既位置垂直點落去個海面個點叫B ship a 叫C ship b 叫D
AB垂直BC BCD為一直線 (其實我係唔想打英文 自己轉翻啦)
AB=300
angleBAC = 28 angleBAD=58
tan28=BC/AB
300tan28=BC
tan58=BD/AB
300tan58=BD
BD-BC=CD
300tan58-300tan28=CD
CD=320.5875
The distance between the two ships are 321m

diagram 一陣補翻

2008-05-18 17:28:09 補充：
http://www.alfa2.info/0611/helicopter&ships.GIF

圖片連結
畫得樣衰
希望諒解

http://hk.myblog.yahoo.com/aludramak/article?new=1&mid=2

Please look at the link above for the picture.

Assume point O is the point directly from the helicopter.

We need to find out distance between A (ship A) and B (ship B).
So it will be OB - OA

Due to the reason of ALT angle, we know that angle HBO = 28 degree
and HAO = 58 degree

tan 58 = 300 / OA
OA = 300 / tan 58
OA = 187.46080557
= 187.461 (to 3 decimal places)

tan 28 = 300 / OB
OB = 300 / tan 28
OB = 564.2179396
= 564.218 (to 3 decimal places)

Threfore:
AB = OA - OB
= 564.218 - 187.461
= 376.757m

NOTE: The definition of angle of depression from the other answer is incorrect...

2008-05-19 04:29:20 補充：
Sorry, it should be:


Threfore:
AB = OB - OA
= 564.218 - 187.461
= 376.757m