Use Sum and Difference Formulas for Cosines and Sines
- $\cos 285 ^ { \circ }$

Multiple Choice

Use Sum and Difference Formulas for Cosines and Sines
- $\cos 285 ^ { \circ }$

A) $\frac { \sqrt { 2 } ( \sqrt { 3 } - 1 ) } { 4 }$
B) $- \frac { \sqrt { 2 } ( \sqrt { 3 } - 1 ) } { 4 }$
C) $- \sqrt { 2 } ( \sqrt { 3 } + 1 )$
D) $- \sqrt { 2 } ( \sqrt { 3 } - 1 )$ Find the exact value of the expression.