Question

the base angle of an isosceles triangle measures 54°. what is the measure of its vertex angle? 27° 36° 54° 72°

Answer 1

vertex angle = 72°

Explanation:

an isosceles triangle has 2 congruent base angles and a vertex angle.

the 3 angles sum to 180° , that is

vertex + 54° + 54° = 180°

vertex + 108° = 180° ( subtract 108° from both sides )

vertex = 72°