An exterior angle at the base of an isosceles triangle measures 140 degrees. what is the measure of the vertex angle?

The correct answer for the question that is being presented above is this one: 40 degrees, 40 degrees, and 100 degrees.

Given that the exterior angle is 140 degrees, then the supplementary angle is = 180 - 140 = 40 degrees.

The vertex angles are the following: 40, 40, and 100.

In the first triangle 80+20+p=180 (since sum of all angles of a triangle is 180)so p= 80also in second triangle 55+45+q=180 (since sum of all angles of a triangle is 180)so q=80so we can conclude that p=80 degrees q=80 degrees so p=q=80 degreeshence option b is correct