不難maths第6回

As shown in the diagram below:

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/April07/Bearing.jpg

Notes:

The 50° is by the fact of alternate angle between parallel lines.
∠AOB is a right angle according to the given.
Hence, sin θ = 1/2
θ = 30°
So the bearing of B from A is given by:
N(50° +θ )S → N80° S

2007-04-08 10:30:26 補充：
感謝 pypy0106 的提示:The answer should be S80°E

唔識！................