luruqing
幼苗
共回答了19个问题采纳率：84.2% 举报
原式=(1+sinA+cosA)/(1+sinA-cosA)
=(1+cosA+sinA)/[(1-cosA)+sinA]
={2[cos(A/2)]^2+2sin(A/2)cos(A/2)}
/{2[sin(A/2)]^2+2sin(A/2)cos(A/2)|
=2(cos(A/2)[cos(A/2)+sin(A/2)]/{2sin(A/2)[sin(A/2)+cos(A/2)]|
=cos(A/2/sin(A/2)
=cot(A/2).
1年前
5
