vertical angle of an isoceles triangle is 100 degree find its base angle

Hi

Verical angle means of triangle ABC is A

angle A = 100

We know that other two angles are same in isosceles triangle

100 + x + x = 180

100 + 2x = 180

2x = 180 - 100

2x= 80

x = 80 / 2

x = 40

**So the base angle is 40 degree**