If N Is an Integer, N · 180° Represents an Integer

Multiple Choice

If n is an integer, n · 180° represents an integer multiple of 180°, and (2n + 1) · 90° represents an odd integer multiple of
90°. Decide whether the expression is equal to 0, 1, -1, or is undefined.
-Find $\sin \theta$ , given that $\cos \theta = \frac { 2 } { 3 }$ and $\tan \theta < 0$ .

A) $- \frac { \sqrt { 5 } } { 2 }$
B) $- \frac { \sqrt { 5 } } { 3 }$
C) $- \frac { 3 } { 2 }$
D) $- \sqrt { 5 }$