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In these lessons, we will learn the following:

- How to form an Angle
- Naming an Angle
- Measuring Angles with a protractor
- Angles around a point (with worksheets)

In geometry, an angle consists of two rays that share the same endpoint. The point where the rays intersect is called the **vertex** of the angle. The two rays are called the **sides** of the angle.

You can name an angle by specifying three points: two on the rays and one at the vertex.

The angle below may be specified as angle ABC or ∠ABC. The vertex point is always given in the middle.

**How to name an angle?**

The vertex is the point where the two rays meet to form an angle.

Angles can be named in three ways:

- By three capital letters, with the vertex letter in the middle. ∠ABC or ∠CBA
- By one capital letter ∠B. This can only be used if ∠B is the only angle it could be.
- By one lower case letter or number written in the middle of the angle.

**Have a look at the following video for more examples on how to name angles**

How to name an angle using three letters

The size of an angle is measured in degrees with the use of a protractor.

A **straight line** has an angle of 180°

Worksheets for Angles in a straight line

**How to use a protractor to measure an angle?**

**How to Measure a Reflex Angle Using a Protractor?**

The sum of angles around a point will always be **360** degrees.

In the diagram above, the sum of the angles is 70° + 55° + 50° + 65° + 120° = 360°

Example 1: Given the diagram below, determine the value of the angle *a.*

Solution:

Step 1: Get the sum of the known angles.

30° + 65° + 150° + 73° = 318°

Step 2: Subtract sum of known angles from 360°

360° – 318° = 42°

Answer: Angle *a* is 42°

Worksheets for Angles Around a Point

**What are angles around a point?**

It will also give some examples of finding angles around a point.

**Problem Solving: Angles Around a Point**

This video discusses relationships among angles around a point.

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