Answer
$30^{\circ},150^{\circ},210^{\circ},330^{\circ}$
Work Step by Step
$4 \sin{\theta} - \dfrac{1}{\sin{\theta}} = 0$
$4 \sin^2{\theta} - 1 = 0$
$4 \sin^2{\theta} = 1$
$\sin^2{\theta} = \dfrac{1}{4}$
$\sin{\theta} = \pm \dfrac{1}{2}$
$\theta = 30^{\circ},150^{\circ},210^{\circ},330^{\circ}$
