Skill: Classify angles

An angle is classified by how wide its turn is, not by which way it points or how long its sides are.

Use a right angle, which measures $90^\circ$, as a benchmark:

• Acute: less than $90^\circ$
• Right: exactly $90^\circ$
• Obtuse: more than $90^\circ$ but less than $180^\circ$

Example

Classify an angle that measures $125^\circ$.

1. Compare $125^\circ$ with $90^\circ$.
2. Since $125^\circ$ is greater than $90^\circ$, the angle is wider than a right angle.
3. Since $125^\circ$ is less than $180^\circ$, it is not a straight angle.

Therefore, an angle measuring $125^\circ$ is obtuse.