Question

One angle on the base of an isosceles triangle is 30°. What is the measure of its vertical angle?​

Answer 1

isosceles triangle means both angle or sides equal so in this way

unknown angle + 30 + 30 = 180°

unknown angle+60=180

so unknown angle=120°

which is vertical angle

Answer 2

120 degrees

Explanation:

vertical angle of isoceles = 180 - 2(base angles) = 180 - 2(30) = 120