Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 5 - Section 5.5 - Trigonometric Equations - Exercise Set - Page 704: 68

Answer

$\{\frac{\pi}{3},\frac{2\pi}{3},\frac{4\pi}{3},\frac{5\pi}{3} \}$

Work Step by Step

Step 1. Use the identity $cos^2x=1-sin^2x$, we have $3-3sin^2x-sin^2(x)=0$ or $4sin^2x=3$, which gives solutions as $sin(x)=\pm\frac{\sqrt 3}{2}$ Step 2. For $sin(x)=\frac{\sqrt 3}{2}$, we can find all x-values in $[0,2\pi)$ as $x=\frac{\pi}{3},\frac{2\pi}{3}$ Step 3. For $sin(x)=-\frac{\sqrt 3}{2}$, we can find all x-values in $[0,2\pi)$ as $x=\frac{4\pi}{3},\frac{5\pi}{3}$ Step 4. The solutions for the original equation in $[0,2\pi)$ are $\{\frac{\pi}{3},\frac{2\pi}{3},\frac{4\pi}{3},\frac{5\pi}{3} \}$
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