The obtuse angle is the space between two lines that share the same vertex whose **inclination or opening is greater than 90 degrees (90°) and less than 180 degrees (180°)** .

The obtuse angles can be found, for example, in the **obtuse** angles since they are characterized precisely by having one of their obtuse angles, that is, greater than 90 degrees and less than 180 degrees.

In geometry, it is important to know how to identify obtuse angles, since, being visually greater than 90 ° (a quarter of a circle), it becomes visually easier to determine, for example, that their supplementary angles (angles that add 180 degrees ) must be acute (less than 90 degrees) and other basic trigonometry operations.

In the classification of triangles, we can find the obtuse angle in a scalene obtuse triangle. This type of triangle is characterized by having an obtuse angle and all its uneven sides. This last characteristic is common to all scalene triangles.

## Types of angles in geometry

The types of basic angles in geometry and trigonometry are as follows:

- Acute angle: angles measuring less than 90°.
- Obtuse angle: angles measuring more than 90°.
- Right angle: angle measuring 90°.
- Plain angle: angle that measures 180°.