### Home > A2C > Chapter 13 > Lesson 13.2.1 > Problem13-96

13-96.

An isosceles triangle has sides with lengths 10, 10, and 5 cm. What are the measures of the angles in the triangle? Homework Help ✎

Find BD.

Which trigonometric ratio should you use to find m ∠ B?

$\text{cos}B=\frac{2.5}{10}=0.25$

$m\angle B=\text{cos}^{-1}(0.25)$

m ∠B ≈ 75.52°

Now that you know the measure of angle B, find the measure of angles A and C.