## Precalculus (6th Edition) Blitzer

$\{0,1.2310, \pi, 5.0522 \}$
Step 1. Rewrite the function as $tan(x)(sec(x)-3)=0$ Step 2. For $tan(x)=0$, we have $x=0, \pi$ Step 3. For $sec(x)=3$, we have $cos(x)=\frac{1}{3}$, which gives the reference angle $x_0=cos^{-1}(\frac{1}{3})\approx1.2310$ and solutions $x_1=x_0=1.2310$, $x_2=2\pi-x_0\approx5.0522$ Step 4. We have the solution set as $\{0,1.2310, \pi, 5.0522 \}$