FTCE General Knowledge Math Practice Test

What type of triangle has all angles measuring less than 90°?

1. Right triangle

2. Obtuse triangle

3. Acute triangle

4. Equilateral triangle

The correct answer is: Acute triangle

The correct answer is that the type of triangle with all angles measuring less than 90° is an acute triangle. In an acute triangle, every angle is acute, meaning each angle measures more than 0° but less than 90°. This characteristic distinguishes it from other types of triangles. While a right triangle contains one angle that is exactly 90°, an obtuse triangle has one angle greater than 90°. Similarly, an equilateral triangle, although it has all angles equal, still features each angle measuring exactly 60°, which fulfills the criteria of being acute, but its definition is based on having equal sides and angles. Thus, focusing strictly on the angle measure, an acute triangle specifically describes the scenario where every angle is less than 90°.