Complex Numbers In Polar Form: Demoivre's Theorem Question?

Question

In the following exercise, write each complex number in rectangular form. If necessary, round to the nearest tenth.

7(cos(3Pi/2) + isin(3Pi/2))

Answer 1

z = 7[cos(3π/2) + isin(3π/2)]
z = 7[0 + i(-1)] = -7i