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...