∫（0,x)sint(x-t)dt
=-∫(0,x)sin(t-x)d(t-x)
=(0,x)[cos(t-x)]
=cos0-cos(-x)
=1-cosx你第二步做错了吧没有，sin(x-t)=-sin(t-x)sint怎么变成sin(t-x)去了哦，看错题了，这得用分部积分法：原式=(-cost)(x-t)+∫ cost* (-1) dt=-(cost)(x-t)-sint=-sinx-[-x]=x-sinx