Evaluate the Cosine of the Angle Without Using a Calculator $30 ^ { \circ }$

Multiple Choice

Evaluate the cosine of the angle without using a calculator. $30 ^ { \circ }$

A) $\frac { \sqrt { 2 } } { 2 }$
B) $- \frac { \sqrt { 2 } } { 2 }$
C) $\frac { \sqrt { 3 } } { 2 }$
D) $\frac { 1 } { 2 }$
E) 0