应该是cost而不是cosx吧x=(e^t)sint, y=(e^t)cost∴dx/dt=(e^t)sint+(e^t)cost=(e^t)(sint+cost)dy/dt=(e^t)cost-(e^t)sint=(e^t)(cost-sint)∴y'=dy/dx=(dy/dt)/(dx/dt)=[(e^t)(cost-sint)]/[(e^t)(sint+cost)]=(co...