提示,分部积分和(1+sinx)/(1+cosx)=1/2*(1+tan(x/2))^2,具体怎么算我也忘了(1+sinx)/(1+cosx)怎么化到1/2*(1+tan(x/2))^21+sin(x)=sin(x/2)^2+cos(x/2)^2+2*sin(x/2)*cos(x/2)=[sin(x/2)+cos(x/2)]^2;1+cos(x)=2*cos(x/2)^2;两个除一下就出来了