## Precalculus (10th Edition)

Published by Pearson

# Chapter 9 - Polar Coordinates; Vectors - 9.4 Vectors - 9.4 Assess Your Understanding - Page 607: 72

#### Answer

$108.44^\circ$

#### Work Step by Step

If $v=ai+bj$ then by definition $tan(\alpha)=\frac{b}{a}$, hence $\alpha=tan^{-1}(\frac{b}{a})$. Also $0^\circ\lt\alpha\lt360^\circ.$ Therefore here $\alpha=tan^{-1}(\frac{3}{-1})=tan^{-1}(-3)=108.44^\circ.$

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