Calculate the angle at the base of an isosceles triangle if the angle at its apex is 116 °.

We are given an isosceles triangle, this is a triangle whose sides are equal to each other. Based on the properties of an isosceles triangle, the angles at the base are also equal.
We have an angle at the apex of an isosceles triangle, it is equal to 116 °. The sum of the angles of any triangle is 180 °. This means that we can find the sum of the angles at the base:
180 ° -116 ° = 64 °.
Find the angle at the base of the triangle:
64 °: 2 = 32 °.
Answer: the angle at an isosceles triangle is 32 °.