令√x=t，则x=t²，dx=2tdt∫sin√xdx=∫sint·2tdt=2∫t·sintdt=-2∫t·d(cost)=-2[t·cost-∫costdt] 分部积分=-2[t·cost-sint]+C=2(sint-t·cost)+C=2(sin√x-√x·cos√x)+C.
