Express the Sum or Difference as a Product $$\cos \frac { 7 x } { 2 } + \cos \frac { 5 x } { 2 }$$

Multiple Choice

Express the sum or difference as a product.
- $$\cos \frac { 7 x } { 2 } + \cos \frac { 5 x } { 2 }$$

A) $2 \cos 3 x \cos \frac { x } { 2 }$
B) $2 \sin 3 x \sin x$
C) $2 \sin 3 x \sin \frac { x } { 2 }$
D) $2 \cos 3 x$