Question

what is cos 30°?
a. √3
b. 1/2
c. 1/√2
d. 1
e 1/√3
f. √3/2

Explanation:

Step1: Recall the cosine formula

In a right - triangle, $\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}$.

Step2: Identify the sides for $\theta = 30^{\circ}$

For the $30 - 60-90$ triangle, the adjacent side to the $30^{\circ}$ angle is $\sqrt{3}$ and the hypotenuse is $2$.

Step3: Calculate $\cos30^{\circ}$

Using the formula $\cos30^{\circ}=\frac{\sqrt{3}}{2}$.

Answer:

F. $\frac{\sqrt{3}}{2}$