Question

if the cosine of an angle θ is 1/2, what is θ? you may assume that 0° ≤ θ ≤ 180°.
(1 point)

Explanation:

Step1: Recall the inverse cosine function

We know that if $\cos\theta = x$, then $\theta=\arccos(x)$. Here $x = \frac{1}{2}$, so $\theta=\arccos(\frac{1}{2})$.

Step2: Use the unit - circle or trigonometric values

On the unit circle, for $0^{\circ}\leq\theta\leq180^{\circ}$, we know that $\cos60^{\circ}=\frac{1}{2}$.

Answer:

$60$