Question

Express the complex number in trigonometric form.

-3i

Choices:
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

First graph -3i in the complex plane as follows...

Answer 2

Next determine the angle that is swept out from the positive R axis to the point -3i like so...