## Precalculus (6th Edition) Blitzer

$\{0,\pm2\pi\}$
Step 1. Rewrite the equation as $sec(x)-1=0$ and define a function $f(x)=sec(x)-1$. Step 2. Graph the function in the interval of $[-2\pi,2\pi]$ as shown in the figure. Step 3. Identify zeros as $x=0,\pm2\pi$ Step 4. We conclude the solution set in $[-2\pi,2\pi]$ is $\{0,\pm2\pi\}$