FTCE General Knowledge Math Practice Test

Which type of triangle has at least two congruent sides?

1. Scalene triangle

2. Equilateral triangle

3. Isosceles triangle

4. Right triangle

The correct answer is: Isosceles triangle

A triangle that has at least two congruent sides is known as an isosceles triangle. This type of triangle is defined specifically by this property: two sides are of equal length, and the angles opposite those sides are also equal. While an equilateral triangle, which has all three sides equal, also contains two sides that are congruent, it is a more specific case of the broader category of isosceles triangles. In contrast, a scalene triangle has all sides of different lengths, meaning it cannot have any congruent sides. A right triangle is defined solely by having one angle measuring 90 degrees and is not dependent on the lengths of the sides, which can be equal or different. Therefore, the most inclusive answer regarding the requirement of having at least two congruent sides is the isosceles triangle.