Write the Complex Number in Trigonometric Form $$r ( \cos \theta + i \sin \theta )$$

Multiple Choice

Write the complex number in trigonometric form $$r ( \cos \theta + i \sin \theta )$$ with θ in the interval [0°, 360°) .
- $4 i$

A) $4 \left( \cos 270 ^ { \circ } + i \sin 270 ^ { \circ } \right)$
B) $4 \left( \cos 0 ^ { \circ } + i \sin 0 ^ { \circ } \right)$
C) $4 \left( \cos 180 ^ { \circ } + i \sin 180 ^ { \circ } \right)$
D) $4 \left( \cos 90 ^ { \circ } + \mathrm { i } \sin 90 ^ { \circ } \right)$