Base angles are the two angles that are opposite the two equal sides in an isosceles triangle. In an isosceles triangle, the two sides that are equal in length are called the legs, and the third side is called the base. The angles opposite the legs are known as the base angles.
For example, consider an isosceles triangle with two sides of equal length. The angles opposite these sides are the base angles. These angles are always equal in measure. This property is one of the key characteristics of an isosceles triangle.
Understanding base angles is important in geometry because it helps in solving various problems related to triangles, such as finding missing angles or sides. The equality of base angles can also be used to prove that a triangle is isosceles.