# 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 $\angle BVA$.