Question

The base angle of an isosceles triangle measures 54 degrees. What is the measure of its vertex angle?

Answer 1

A triangle always has 180 degrees.

An isosceles triangle has 2 congruent base angles and 1 vertex angle.
Base + base + vertex = 180

54+ 54+ x = 180
108 + x = 180

X = 72
72 is the measure of the vertex angle

Answer 2

Vertex Angle = 180 -54 -54Vertex Angle =72 degrees