When $\sin \theta + 3 \cos \theta = 0$ and $\cos ( \pi - \theta ) > 0$, what is the value of $\sin \theta$? [3 points]\\
(1) $\frac { 3 \sqrt { 10 } } { 10 }$\\
(2) $\frac { \sqrt { 10 } } { 5 }$\\
(3) 0\\
(4) $- \frac { \sqrt { 10 } } { 5 }$\\
(5) $- \frac { 3 \sqrt { 10 } } { 10 }$