Use Identities to Find the Exact Value $$\cos \frac { 7 \pi } { 12 } \cos \frac { 5 \pi } { 12 } + \sin \frac { 7 \pi } { 12 } \sin \frac { 5 \pi } { 12 }$$

question 173

Multiple Choice

Use Identities to find the exact value.
- $$\cos \frac { 7 \pi } { 12 } \cos \frac { 5 \pi } { 12 } + \sin \frac { 7 \pi } { 12 } \sin \frac { 5 \pi } { 12 }$$

• A) \(\frac { \sqrt { 3 } } { 2 }\)
• B) \(- 1\)
• C) \(\frac { 1 } { 2 }\)
• D) \(\frac { \sqrt { 2 } } { 2 }\)