The terminal side of angle \( \theta \) is in quadrant III, and the value of \( \sin \theta = - \frac { 3 } { 8 } \) . What are the exact values of \( \sin \theta , \cos \theta , \) and \( \tan \theta \) ? Work:
The value of \( x = \)
The value of \( y = \)
The value of \( r = \)
The terminal side of the angle passes through quadrant