Polar Coordinates and Differentiation Practice Test

If a path is modeled by $r=\sin(2\theta)$, what is $\frac{dy}{dx}$ at $\theta=\frac{\pi}{4}$?​

For the polar curve $r=2\sin\theta+\cos\theta$, what is $\frac{dy}{dx}$ at $\theta=\frac{\pi}{2}$?