Question

In an isosceles triangle the vertex angle is twice either base angle. ( Let the base angle be b in degrees. Remember that the sum of angle of a triangle is 180 degrees

Answer 1

vertex angle= 2b
base angle 1=b
base angle 2=b

since the sum of all angles is 180, we can confirm that:

2b+b+b=180
4b=180
b=180/4
b=45

therefore each of the base angles are 45 deg and the vertex measures 45*2 which is 90 deg

hope it helps :D