Answer:

1. What do you call the congruent sides of an isosceles triangle? How about its third side?

• an isosceles triangle is a triangle that has at least two congruent sides. The congruent sides of an isosceles are called the legs, the third side is called the base.

2. What is the relationship of the base angles of an isosceles triangle?

• the base angles of an isosceles triangle are the angles formed by the base and one leg of the triangle. The base angle theorem states that in an isosceles triangle, the angles opposite the congruent sides are congruent. Therefore, the base angles of an isosceles triangle are congruent.

3. What do you call the angle included by the legs of an isosceles triangle?

• the angle included by the legs is called the vertex angle.