Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 7 - Review - Exercises - Page 578: 41

Answer

$\frac{\pi}{6}$, $\frac{\pi}{2}$, $\frac{5\pi}{6}$, $\frac{7\pi}{6}$, $\frac{3\pi}{2}$, $\frac{11\pi}{6}$

Work Step by Step

$\tan \frac{1}{2}x+2\sin 2x=\csc x$ $\frac{1-\cos x}{\sin x}+2*2\sin x\cos x=\frac{1}{\sin x}$ Multiply both sides by $\sin x$: $1-\cos x+4\sin^2x\cos x=1$ $-\cos x+4\sin^2x\cos x=0$ $\cos x(-1+4\sin^2x)=0$ $\cos x(4\sin^2x-1)=0$ $\cos x(2\sin x+1)(2\sin x-1)=0$ If $\cos x=0$, then the only solutions in $[0, 2\pi)$ are $\frac{\pi}{2}$ and $\frac{3\pi}{2}$. If $2\sin x+1=0$, then $2\sin x=-1$, ad $\sin x=-\frac{1}{2}$. The only solutions in $[0, 2\pi)$ are $\frac{7\pi}{6}$ and $\frac{11\pi}{6}$. If $2\sin x-1=0$, then $2\sin x=1$, ad $\sin x=\frac{1}{2}$. The only solutions in $[0, 2\pi)$ are $\frac{\pi}{6}$ and $\frac{5\pi}{6}$.
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