∫(cosx)^4dx/(sinx^3)=∫(cosx)^3dsinx/sinx^3=(-1/2)∫cosx^3d(1/sinx^2)=(-1/2)cosx^3/sinx^2-(3/2)∫(1-sinx^2)dx/sinx=(-1/2)cosx^3/sinx^2-(3/2)cosx+(3/4)ln|(1+cosx)/(1-cosx)|+C 楼上的正负号弄错了...