Answer
$0.34+k\pi$, $2.80+k\pi$
Work Step by Step
$9\sin^2\theta-1=0$
$9\sin^2\theta=1$
$\sin^2\theta=\frac{1}{9}$
$\sin\theta=\pm\frac{1}{3}$
If $\sin\theta=\frac{1}{3}$, then $\theta=0.34+2k\pi$ or $\theta=2.80+2k\pi$.
If $\sin\theta=-\frac{1}{3}$, then $\theta=3.48+2k\pi$ or $\theta=5.94+2k\pi$.
Combining the two, we get $\theta=0.34+k\pi$ or $\theta=2.80+k\pi$.
