The sum of all values of $\theta \in [ 0,2 \pi ]$ satisfying $2 \sin ^ { 2 } \theta = \cos 2 \theta$ and $2 \cos ^ { 2 } \theta = 3 \sin \theta$ is\\ (1) $4 \pi$\\ (2) $\frac { 5 \pi } { 6 }$\\ (3) $\pi$\\ (4) $\frac { \pi } { 2 }$