FTCE General Knowledge Math Practice Test

Which triangle is described by having exactly two equal sides?

1. Scalene triangle

2. Equilateral triangle

3. Obtuse triangle

4. Isosceles triangle

The correct answer is: Isosceles triangle

The triangle that has exactly two equal sides is known as an isosceles triangle. This type of triangle is characterized by the presence of two sides that are of the same length, which leads to two angles within the triangle also being equal. This specific property of having two equal sides distinguishes isosceles triangles from other types of triangles, as they may have different arrangements of side lengths and angles. In contrast, a scalene triangle has all sides of different lengths and no equal angles. An equilateral triangle has all three sides equal, making it a special case of an isosceles triangle but not the correct answer here since it does not meet the criteria of having exactly two sides equal. An obtuse triangle refers to a triangle with one angle greater than 90 degrees, which does not specifically relate to the lengths of its sides. Thus, isosceles is the precise term to describe the triangle with exactly two equal sides.