Types of angles

In a nutshell

There are four main way to classify angles: acute, right, obtuse and reflex. Angles can also be represented using three-letter notation.

Types of angles

Here are the four types of angles you need to know:

NAME	DESCRIPTION	DIAGRAM
Acute angles	Angles that are less than $$90\degree$$​​
Right angles	Angles that are exactly $$90\degree$$​​
Obtuse angles	Angles that are between $$90\degree$$ and $$180\degree$$​​
Reflex angles	Angles that are between $$180\degree$$ and $$360\degree$$​​

Three-letter angle notation

Three-letter angle notation is a way of referring to angles in shapes. It is represented using the angle symbol ($$\angle$$​) followed by three capital letters. The angle being referred to is the middle letter.

Example

Express the given angle in three-letter notation:

The angle is at the point $$V$$, and the lines extend to the points $$A$$ and $$B$$.

Hence, the angle is written as $$\angle AVB$$ in three-letter notation.

The given angle is written as $$\underline{\angle AVB}$$.

Note: It is also acceptable to write the angle as $$\angle BVA$$.