Question

question 2 of 30
evaluate \\( \cos 300 ^ { \circ } \\) without using a calculator.
a. \\( - \frac { 1 } { 2 } \\)
b. \\( - \frac { \sqrt { 3 } } { 2 } \\)
c. \\( \frac { \sqrt { 3 } } { 2 } \\)
d. \\( \frac { 1 } { 2 } \\)

Explanation:

Step1: Find reference angle

$300^\circ$ is in Quadrant IV. Reference angle = $360^\circ - 300^\circ = 60^\circ$.

Step2: Cosine in Quadrant IV

Cosine is positive in Quadrant IV. $\cos 60^\circ = \frac{1}{2}$. So $\cos 300^\circ = \cos 60^\circ$.

Answer:

D. $\frac{1}{2}$