参考以下
∫sinx/(1+sinx)dx
=∫(1+sinx-1)/(1+sinx)dx
=∫[1-1/(1+sinx)]dx
=∫dx-∫dx/(1+sinx)
=x-∫dx/[sin²(x/2)+cos²(x/2)+2sin(x/2)cos(x/2)]
=x-∫dx/[sin(x/2)+cos(x/2)]²
=x-∫sec²(x/2)/[tan(x/2)+1]²dx
=x-∫d[tan(x/2)]/[tan(x/2)+1]²dx
=x-∫d[tan(x/2)+1]/[tan(x/2)+1]²dx
=x+1/[tan(x/2)+1]+C (C是积分常数)