The total number of degrees in the center is 360 degrees If all five vertex angles meeting at the center are congruent, what is the measure of a base angle of one of the triangles?

The five congruent angles at the center divide 360 degrees equally, so each triangle’s vertex angle is 360 ÷ 5 = 72 degrees. The two base angles of each isosceles triangle are equal and together measure 180 − 72 = 108 degrees, so each is 108 ÷ 2 = 54 degrees. The correct choice is 54 degrees.

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