Find the trigonometric form of the complex number shown below. $- 3 i$
A) $3 ( \cos 0 + i \sin 0 )$
B) $3 ( \cos \pi + i \sin \pi )$
C) $3 \left( \cos \frac { 3 \pi } { 2 } + i \sin \frac { 3 \pi } { 2 } \right)$
D) $3 \left( \cos \frac { \pi } { 4 } + i \sin \frac { \pi } { 4 } \right)$
E) $3 \left( \cos \frac { \pi } { 2 } + i \sin \frac { \pi } { 2 } \right)$

Question

Quizplus · Accepted Answer

The trigonometric form of a complex number is $r(\cos \theta + i\sin \theta)$, where $r$ is the magnitude of the complex number and $\theta$ is the argument. For $-3i$, $r = 3$ and $\theta = \frac{3\pi}{2}$, because the point lies on the negative imaginary axis.

Find the Trigonometric Form of the Complex Number Shown Below −3i- 3 i−3i

Find the Trigonometric Form of the Complex Number Shown Below $- 3 i$