FTCE General Knowledge Math Practice Test

Which triangle contains one right angle?

1. Obtuse triangle

2. Acute triangle

3. Scalene triangle

4. Right triangle

The correct answer is: Right triangle

A triangle that contains one right angle is classified as a right triangle. By definition, a right triangle has one angle that measures exactly 90 degrees, which is the defining characteristic that sets it apart from other types of triangles. Obtuse triangles have one angle greater than 90 degrees, which would make them incompatible with the definition of a right triangle. Acute triangles, on the other hand, consist entirely of angles less than 90 degrees, thus lacking any right angles. Scalene triangles can have any angle measures but are defined by having all sides of different lengths and do not necessarily contain a right angle. Therefore, the only option that properly describes a triangle with one right angle is the right triangle.