Question

-3i

3(cos 180° + i sin 180°)

3(cos 270° + i sin 270°)

3(cos 90° + i sin 90°)

3(cos 0° + i sin 0°)

Answer 1

\[\Large\rm =3(0-\mathcal i)\]So let's look at this in the complex plane.

Answer 2

So what angle do we have?