Using a Protractor
- 1. Using a Protractor Geometry Lesson
- 3. 3 A 180o Protractor Outside scale from 0o to 180o going in a clockwise direction. Inside scale from 0o to 180o going in an anti-clockwise direction.
- 4. 16-Apr-20 4 You need to be able to measure an angle to the nearest degree. To help you do this you should always: 1. Look directly down onto the cross point. 2. Always use the protractor in a horizontal manner as shown below.
- 5. Measuring Angles with a Protractor Place the center point of the protractor on the vertex of the angle.
- 6. Measuring Angles with a Protractor Read where the top ray crosses the protractor. (Identifying your angle as acute or obtuse will help you know whether to use the top or bottom set of numbers)
- 7. Measuring Angles with a Protractor Therefore this angle has a measure of 50°
- 8. 8 1 2 Measuring Angles with a 180o Protractor 0 on the outside so use outside scale 0 on the inside so use inside scale 67o 50o
- 9. 9 3 4 Measuring Angles with a 180o Protractor 0 on the outside so use outside scale 0 on the inside so use inside scale 135o 120o
- 10. Drawing Angles with a Protractor The first step should be to extend the rays that form the angle using a straight edge or a ruler.
- 11. ACTIVITY 1. Using a protractor, draw the following angles with the given measures. 1. 85° 2. 15° 3. 140°