In an isosceles triangle ABC with a base BC, the angle BAC is known to be 80 °. Find the angle ABC.

We know. that this triangle is isosceles. An isosceles triangle is a triangle that has two sides equal and also has equal angles at the base.

The vertex angle is known to be 80 °. This means that you can find the angle at the base.

The angles of a triangle always add up to 180 degrees. So, let’s make an equation, denoting the angle at the base for x.

x + x + 80 = 180;

Let’s transfer the known numbers to the other side:

2x = 100;

Find x by freeing the variable x from the coefficient. To do this, divide both sides of the equation by 2:

x = 50.

Answer: 50 °.