# 8.4.4. Corollaries of Isosceles Triangle Theorems

Given that the measure of the base angle of an isosceles triangle is one-fourth that of its vertex angle, determine the measure of the apex angle.

- A
- B
- C
- D

### Example

Given that the measure of the base angle of an isosceles triangle is one-fourth that of its vertex angle, determine the measure of the apex angle.

### Solution

An isosceles triangle has 2 base angles that are equal in measure.

Write an equation to show that the sum of the triangle's angle
measures is

So, the vertex angle has a measure of