Complex Numbers in Rectangular, Polar Form Practice Test

Find the polar form of $-5i$ as $r(\cos\theta + i\sin\theta)$ with $\theta$ in degrees, where $r=\sqrt{a^2+b^2}$ and $\theta$ is the argument measured from the positive real axis.

Convert $3\left(\cos 60^\circ+i\sin 60^\circ\right)$ to rectangular form $a+bi$ using $a=r\cos\theta$ and $b=r\sin\theta$.