Trigonometry! #109

In $\Delta ABC$ , $\angle A>\angle B$ . If the measures of angles $A$ and $B$ satisfy the equation $3\sin x - 4\sin^{3}x-k=0$ for $0<k<1$ , then find the measure of $\angle C$ .

Express your answer in the form of $\ \frac{p\pi}{q}$ where $p$ and $q$ are coprime integers. Enter the value of $pq$ .

This problem is part of the set Trigonometry .