Answer
$-7i$
Work Step by Step
We know that $\cos270^{\circ}=0$ and $\sin270^{\circ}=-1$
Substituting these values in the expression and solving:
$7(\cos270^{\circ}+i\sin270^{\circ})=7(0-1i)=-7i$
Trigonometry (10th Edition)
by Lial, Margaret L.; Hornsby, John; Schneider, David I.; Daniels, Callie
Published by
Pearson
ISBN 10:
0321671775
ISBN 13:
978-0-32167-177-6
Chapter 8 - Quiz (Sections 8.1-8.4) - Page 379: 6c
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