$x=\cos \theta-\cos 2\theta$ and $y=\sin \theta-\sin 2\theta$. What is $\frac{dy}{dx}$?

$\frac{\cos 2\theta-2\cos \theta}{2\sin 2\theta-\sin \theta}$ $\frac{\cos \theta-2\cos 2\theta}{2\sin \theta-\sin 2\theta}$ $\frac{\cos 3\theta-2\cos 2\theta}{2\sin 2\theta-\sin \theta}$ $\frac{\cos \theta-2\cos 2\theta}{2\sin 2\theta-\sin \theta}$

$\frac{\cos \theta-2\cos 2\theta}{2\sin 2\theta-\sin \theta}$

$\frac{dx}{d\theta}=2\sin 2\theta-\sin \theta$, $\frac{dy}{d\theta}=\cos\theta-2\cos2\theta$. Hence $\frac{dy}{dx}=\frac{dy}{d\theta}/\frac{dx}{d\theta}=\frac{\cos \theta-2\cos 2\theta}{2\sin 2\theta-\sin \theta}$