z=e^cost-2sint
dz=e^cost*dcost-2costdt
=-sinte^cost*dt-2costdt
dz/dt=-sinte^cost-2cost
炒的
z=e^cost-2sint
dz=e^cost*dcost-2costdt
=-sinte^cost*dt-2costdt
dz/dt=-sinte^cost-2cost
dz/dt=dz/dx*dx/dt+dz/dy*dy/dt=-sin(t)*e^(cos(t))-2sin(t)
e^cost*(-sint)-2cost
z=-e^cost*sint-2cost