1. Angle Measurements
Reading A Protractor

2. Degrees: Measuring Angles
We measure the size of an angle using degrees.
Example: Here are some examples of angles and
their degree measurements.

3. Protractor A device used to measure angles.

4. Subject: Reading a Protractor Which side of a protractor scale do you use?
Subject: Re: Reading a Protractor
I think that the easiest way to decide which scale to use is to look at the angle
you're measuring. If it is greater than a right angle (more than ninety degrees)
then use the scale that has numbers greater than 90. If the angle is obviously
acute (measures less than 90 degrees), use the scale which has numbers
less than 90. Of course you have to line up the protractor correctly with
the center point on the vertex of the angle and one of the rays of the angle
coincide with the line on the protractor. Happy measuring!

5. Acute: Less Than 90 degrees Obtuse: Greater than 90 degrees
Angle Review
Acute: Less Than 90 degrees
Obtuse: Greater than 90 degrees
Right: 90 Degrees

6. Sample Acute Angles
Most Suitable for Roof Slopes

7. Sample Obtuse Angles
Not Suitable for Roof Slopes

8. Relating Angles to Roof slopes
Acute Angles Are Used For Roofs
Angles Greater Than 45 Degrees Are Considered To Be Steep Slopes
Angles Between Degrees Are Typical Angles Used For Roof Slopes
Angles Less Than 20 Degrees Are Considered To Be Low Roof Slopes

9. Let’s Review
Look At Each Of The Following Angles A-E. State whether the angle is Obtuse or Acute.
Determine approximately what you think the degree of the angle is by comparing it to the protractor.
State whether it is a low slope, normal slope, or non usable slope for a roof.

10. B A C E D