Concept

An angle is the figure formed by two rays, called the sides of the angle, sharing a common endpoint, called the vertex of the angle.
The sides of an angle are two rays that share a common endpoint called the vertex of the angle.
The vertex of an angle is the point where the two sides of an angle meet.

A protractor is used to measure and draw angles. There are two sets of degrees along the edge of the protractor: an inner and outer scale. Both scales go from 0 to 180 degrees, but they run in opposite directions. Each mark on the protractor is 1 degree.
The baseline, also known as the zero edge, has a small circle at its midpoint. This is the center mark or origin point. 

Rule

How to draw an angle using a protractor:

1. Draw a ray (one side of the angle)
2. Place the center mark on the endpoint of the ray.
3. Starting from zero degrees, find the desired degree of the angle and make a mark.
4. Draw a ray from the vertex to the drawn mark.
5. The drawn angle will be the desired angle.

Example

Use the slider and draw an angle of 100 degrees.

Solution

On the given protractor, one side is lined up with zero on the outer scale. Note where the 100 is located on the outer scale. Use the slider to draw the ray at 100. The drawn angle will be at 100 degrees.

Pre-requisite Skills

Measuring Angles (4.10.1)