Answer
$90^{\circ},330^{\circ},210^{\circ}$
Work Step by Step
$2 \sin{\theta} - 1 = \dfrac{1}{\sin{\theta}}$
$2 \sin^2{\theta} - \sin{\theta} - 1 = 0$
Using the quadratic formula:
$\sin{\theta} = \dfrac{1 \pm \sqrt{1-4(2)(-1)}}{2(2)} = \dfrac{1 \pm 3}{4}$
$\sin{\theta} = 1 \hspace{20pt} \text{ or } \hspace{20pt} \sin{\theta} = -\dfrac{1}{2}$
$\theta = 90^{\circ},330^{\circ},210^{\circ}$
