Find the Exact Value of the Given Expression Using a Sum

Multiple Choice

Find the exact value of the given expression using a sum or difference formula.
$\cos \frac { 7 \pi } { 12 }$

A) $\frac { \sqrt { 3 } - 1 } { 2 \sqrt { 2 } }$
B) $\frac { - \sqrt { 3 } - 1 } { 2 \sqrt { 2 } }$
C) $\frac { \sqrt { 3 } + 1 } { 2 \sqrt { 2 } }$
D) $\frac { - \sqrt { 3 } + 1 } { 2 \sqrt { 2 } }$