Polar Coordinates and Complex Numbers · Medium problem

$6\left(\cos180^\circ+i\sin180^\circ\right)$

$5\left(\cos180^\circ+i\sin180^\circ\right)$

$-5\left(\cos180^\circ+i\sin180^\circ\right)$

$10\left(\cos180^\circ+i\sin180^\circ\right)$