maths question

As follows:

圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/02-94.jpg


圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/03-74.jpg


2010-06-25 17:28:22 補充：
http://i707.photobucket.com/albums/ww74/stevieg90/02-94.jpg
http://i707.photobucket.com/albums/ww74/stevieg90/03-74.jpg

2010-06-26 00:02:56 補充：
Then can I use sine law?

2010-06-26 14:20:55 補充：
um..........Let me think...

2010-06-27 15:46:40 補充：
I think this kind of question requires the use of sine/cosine law....
or is it Mathematical Olympiad question??

2010-06-27 17:35:36 補充：
I think using sine/cosine law is the easiest way to solve the Q...also, I think sine/cosine law will be taught in Form 4...

PLS do not use cosine law..

2010-06-26 11:47:13 補充：
As i can't using cosine/sine/tangent law to do this question, can u using other simpier and quicker method to do.? THX for your work hard and pls teach me other method...

2010-06-27 17:19:19 補充：
this is only a F.4 maths question.. can u think of simpier method to teach me.. thx.