∫xcosx/(sinx)^3dx
问题描述：
∫xcosx/(sinx)^3dx
答
=∫x/sin³xdsinx
=∫x/(-2)d[1/sin²x)]
=(-1/2)∫xd(cscx)
=-(1/2)x*csc²x+(1/2)∫csc²xdx
=-(1/2)x*csc²x-(1/2)cotx+C