✔ 最佳答案
first: X+B=90
therefore: X=90-B
put X=90-B into X, so
sin(sin X cos B + sin B cos X )
------------
(1 - sin)
sin[sin (90-B) cos B + sin B cos (90-B) ]
=----------------
cos
sin(cos + sin)
=-------
cos
sin
=--
cos
=1
*remember that sin (90-B) = cos B
2008-07-05 14:41:55 補充:
oh..i am so sorry..我不知道為何2次方會無法顯示出來..
讓我再打一次吧^^
sin^2(sin X cos B + sin B cos X )
------------
(1 - sin^2)
sin^2[sin (90-B) cos B + sin B cos (90-B) ]
=----------------
cos^2
sin^2(cos^2 + sin^2)
=-------
cos^2
sin^2
=--
cos^2
=1
*remember that sin^2 (90-B) = cos^2 B