FTCE General Knowledge Math Practice Test

Which of the following angles is defined as exactly 90°?

1. Straight angle

2. Right angle

3. Acute angle

4. Obtuse angle

The correct answer is: Right angle

A right angle is defined as exactly 90°. It is one of the fundamental types of angles in geometry and is often represented by a square corner. Right angles are crucial in various fields such as mathematics, engineering, and architecture, as they provide a standard measurement for determining perpendicular lines and the construction of various shapes and figures. In contrast, a straight angle measures 180°, representing a straight line, indicating that it encompasses two rays going in opposite directions. An acute angle measures less than 90°, representing angles that are sharp and less than a quarter of a circle. An obtuse angle exceeds 90° but is less than 180°, making it wider than a right angle but not as wide as a straight angle. Understanding these distinctions helps in identifying angles and solving related geometric problems effectively.