Answer
$\{0^{o}, 45^{o},225^{o}\}$
Work Step by Step
Using the zero product principle, either
1. $\quad \tan\theta-1=0\quad$or
2. $\quad \cos\theta-1=0$
$1.\quad\tan\theta=1$
$\theta=45^{o}\quad$or $\theta=45^{o}+180^{o}=225^{o}$
$2.\quad\cos\theta=1$
$\theta=0^{o}$
Solution set = $\{0^{o}, 45^{o},225^{o}\}$
