Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 9 - Analytic Geometry - Section 9.2 The Parabola - 9.2 Assess Your Understanding - Page 669: 82

Answer

$sin\theta =\frac{5\sqrt {89}}{89}\\ cos\theta =-\frac{8\sqrt {89}}{89}\\ cot\theta =-\frac{8}{5}\\ sec\theta =-\frac{\sqrt {89}}{8}\\ csc\theta =\frac{\sqrt {89}}{5}$

Work Step by Step

1. Given $tan\theta=-\frac{5}{8}$ ($\theta$ in quadrant II), let $x=-8, y=5$, we have $r=\sqrt {64+25}=\sqrt {89}$. 2. Thus $sin\theta=\frac{y}{r}=\frac{5\sqrt {89}}{89}$, $cos\theta=\frac{x}{r}=-\frac{8\sqrt {89}}{89}$, $cot\theta=\frac{x}{y}=-\frac{8}{5}$, $sec\theta=\frac{r}{x}=-\frac{\sqrt {89}}{8}$, $csc\theta=\frac{r}{y}=\frac{\sqrt {89}}{5}$
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