In an isosceles triangle, how many sides are equal?

In an isosceles triangle, two sides are equal in length. This distinct characteristic sets isosceles triangles apart from other types of triangles. The two equal sides are referred to as the legs, while the third side, which may differ in length, is known as the base. The equality of these two sides also results in equal angles opposite those sides, contributing to various properties that are useful in geometry.

The definition of an isosceles triangle is rooted in this relationship of having exactly two sides equal, which is the reason why the choice indicating two equal sides is the correct answer. Triangles that have all three sides equal are classified as equilateral, while those with no equal sides are termed scalene.