At their point of intersection, the angle $\theta$ between any two nonparallel lines satisfies the relationship $\left(m_{2}-m_{1}\right) \cos \theta=$ $\sin \theta+m_{1} m_{2} \sin \theta,$ where $m_{1}$ and $m_{2}$ represent the slopes of the two lines. Rewrite the equation in terms of a single trig function.