Answer:
B. [tex]72^{o}[/tex]
Step-by-step explanation:
An isosceles triangle has two equal sides and angles (called base angles).
From the question, the common vertex of 5 congruent isosceles triangles are joined. Thus, creating a regular pentagon which has five sides.
Given that the five congruent triangles form a total of 360° at the center, then;
the measure of a base angle of one of the triangles = [tex]\frac{360^{o} }{5}[/tex]
= [tex]72^{o}[/tex]
