Suppose That Point $P \left( \frac { \sqrt { 5 } } { 5 } , - \frac { 2 \sqrt { 5 } } { 5 } \right)$

Multiple Choice

Suppose that point $P \left( \frac { \sqrt { 5 } } { 5 } , - \frac { 2 \sqrt { 5 } } { 5 } \right)$ is on the unit circle. Find $\sin t$ and $\cos t$

A) $\sin t = - \frac { 2 \sqrt { 5 } } { 5 } , \quad \cos t = \frac { \sqrt { 5 } } { 5 }$
B) $\sin t = - \frac { \sqrt { 5 } } { 5 } , \quad \cos t = \frac { \sqrt { 5 } } { 5 }$
C) $\sin t = \frac { \sqrt { 5 } } { 5 } , \quad \cos t = - \frac { 2 \sqrt { 5 } } { 5 }$
D) $\sin t = 2 \sqrt { 5 } , \cos t = \frac { \sqrt { 5 } } { 5 }$
E) none of these