Question

Does anyone know this?

Answer 1

if the exterior angle of the base is 100 them the measure of the angle at each base is 20 and the measure of the angle of vertex is 100

Explanation:

Given the isosceles triangle has an exterior angle of a base as 100

Let, triangle ABC be an isosceles triangle.

BC is base and C is vertex

Where Angle B = Angle A

We know that the exterior angle of the triangle is the sum of corresponding interior angles

Hence,

Angle A + Angle C = 100.

From property of triangle,

Angle A + Angle B + Angle C =180

100 + Angle B =180

Angle B =180-100=80 is angle at base

Now,

Angle B = Angle A = 80

Angle A + Angle C = 100.

80 + Angle C = 100.

Angle C =20 is angle as Vertex.