The Point P(x, Y) on the Unit Circle That Corresponds $\left( - \frac { \sqrt { 39 } } { 8 } , \frac { 5 } { 8 } \right) \quad$

Multiple Choice

The point P(x, y) on the unit circle that corresponds to a real number t is given. Find the values of the indicated
trigonometric function at t.
- $\left( - \frac { \sqrt { 39 } } { 8 } , \frac { 5 } { 8 } \right) \quad$ Find $\cos \mathrm { t } .$

A) $- \frac { \sqrt { 39 } } { 8 }$
B) $\frac { 5 } { 8 }$
C) $- \frac { \sqrt { 39 } } { 5 }$
D) $- \frac { 8 \sqrt { 39 } } { 39 }$