Skill: Draw angles of a specified measure

An angle is made by two rays that share the same endpoint, called the vertex. The angle’s measure tells how much one ray turns from the other. We measure this turn in degrees, from $0^\circ$ to $180^\circ$.

To draw an angle with a protractor:

1. Draw one ray and mark its endpoint. This endpoint is the vertex.
2. Place the protractor so its center point is exactly on the vertex.
3. Line up the ray with the protractor’s $0^\circ$ line.
4. Find the stated measure on the scale that starts at $0^\circ$ along your ray.
5. Make a small mark at that measure.
6. Use a ruler to draw a second ray from the vertex through the mark.

Example: Draw a $70^\circ$ angle

1. Draw a ray pointing to the right. Mark its endpoint as the vertex.
2. Place the protractor’s center on the vertex.
3. Line up the ray with the protractor’s $0^\circ$ line.
4. Starting from the scale that begins at $0^\circ$ on the right, find $70^\circ$.
5. Make a small mark at $70^\circ$.
6. Remove the protractor and draw a ray from the vertex through the mark.

The two rays now form an angle measuring $70^\circ$. The rays can be short or long, and the angle can point in different directions; the important part is the amount of turn between the rays.