将(x+sin(x))/(1+cos(x))分开成 x/2(cos(x/2))^2+tan(x/2)
+右边的积分就不说了．左边的是用分部积分算．x=U
V'=d(tan(x/2))=2(cos(x/2))^2dx.再由UV'=UV-U'V的分部积分就可以．
用软件算了下结果是
0.5*pi