# Arm of An Angle Definition

The **rays or lines used in forming an angle** are known as an **arm of an angle**.

These **rays have a common joining point** that **makes an angle** that is also known as the **vertex**.

You can determine the measure of an angle by calculating the distance between two arms of an angle.

For a more precise understanding of a concept, let's have a look at the diagram listed below:

**Note:**

If you want to know about angles, you can use our Angle Definition.

Here, **A **and **B **are the arms of an angle, whereas **O** is the joining point of the lines, also known as the vertex, making an angle.