Use the Formula for the Cosine of the Difference of Two

Multiple Choice

Use the Formula for the Cosine of the Difference of Two Angles
- $\cos \left( \frac { 5 \pi } { 12 } \right) \cos \left( \frac { \pi } { 4 } \right) + \sin \left( \frac { 5 \pi } { 12 } \right) \sin \left( \frac { \pi } { 4 } \right)$

A) $\cos \left( \frac { \pi } { 6 } \right)$
B) $\cos \left( \frac { \pi } { 3 } \right)$
C) $\cos \left( \frac { 2 \pi } { 3 } \right)$
D) $\cos \left( \frac { 5 \pi } { 6 } \right)$ Find the exact value of the expression.