Answer
(a) See the graph
(b)
$r=10$
$θ=\frac{3\pi}{2}$
(c)
$z=10(cos\frac{3\pi}{2}+i~sin\frac{3\pi}{2})$
Work Step by Step
(b)
$r=|z|=\sqrt {a^2+b^2}=\sqrt {0^2+(-10)^2}=\sqrt {100}=10$
The point lies in the negative imaginary axis. So:
$θ=\frac{3\pi}{2}$
(c)
$z=r(cos~θ+i~sin~θ)$
$z=10(cos\frac{3\pi}{2}+i~sin\frac{3\pi}{2})$
