：(1+sin x-cos x)/(1+sin x+cos x)
=[1+2sin(x/2)cos(x/2)-(1-2sin(x/2)^2]/[1+2sin(x/2)cos(x/2)+2cos(x/2)^2-1]
=[2sin(x/2)cos(x/2)+2sin(x/2)^2]/[2sin(x/2)cos(x/2)+2cos(x/2)^2]
=2sin(x/2)[cos(x/2)+sin(x/2)]/{2cosx/2*[sin(x/2)+cos(x/2)]}
=sin(x/2)/cos(x/2)
=tanx/2
√希望你能看懂,你能明白,赞同