\begin{align*} D = \frac{\arcsin{(X \sin{\theta})} - \theta}{\sin{\theta}} \end{align*} and \begin{align*} X \sim \text{Uniform}[-1, 1], \hspace{0.5in} \theta \sim \text{Uniform}[0, 2 \pi] \end{align*}
How to find the PDF of $D$? or is there anyway to simplify the equation of $D$!?