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)

Related Topics:

More Geometry Lessons

Geometry Worksheets

Geometry Games

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.

Have a look at the following video for another example on naming angles.

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

The following video will show you 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

The following video illustrates 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.