求助这道题要如何去解决

用公式 (uv)'=u'v+uv'x=(e^t)sin(2t)，y=(e^t)cost.dx/dt=(e^t)'sin(2t)+(e^t)[sin(2t)'=(e^x)sin(2t)+(e^x)*2cos(2t)=(e^x)[sin(2t)+2cos(2t)].y'=(e^t)'cost+(e^t)(cost)'=(e^t)cost+(e^t)(-sint)=(e^t)(cost-sint).dy/dx=(dy/dt)/(dx/dt)=(cost-sint)/[sin(2t)+2cos(2t)]