Find the Exact Value of the Expression If θ = $f ( \theta ) = \cos \theta \quad$

Multiple Choice

Find the exact value of the expression if θ = 30°. Do not use a calculator.
- $f ( \theta ) = \cos \theta \quad$ Find $[ f ( \theta ) ] ^ { 2 }$ .

A) $\frac { \sqrt { 3 } } { 2 }$
B) $\sqrt { 3 }$
C) $\frac { 3 } { 4 }$
D) $\frac { 1 } { 4 }$