Question

for the right triangle below, find the measure of the angle. 18 13 <--? degrees

Explanation:

Step1: Identify cosine - ratio

Let the angle be $\theta$. In a right - triangle, $\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}$. Here, the adjacent side to the angle $\theta$ is 13 and the hypotenuse is 18. So, $\cos\theta=\frac{13}{18}$.

Step2: Find the angle

We use the inverse - cosine function, $\theta = \cos^{-1}(\frac{13}{18})$. Using a calculator, $\theta=\cos^{-1}(\frac{13}{18})\approx43.3^{\circ}$.

Answer:

$43.3$