AngleMeasurements

READING A PROTRACTOR

DEGREES: MEASURING ANGLES

• WE MEASURE THE SIZE OF AN ANGLE USING DEGREES.

• EXAMPLE: HERE ARE SOME EXAMPLES OF ANGLES AND

• THEIR DEGREE MEASUREMENTS.

PROTRACTORA DEVICE USED TO MEASURE ANGLES.

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 numbersless 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 anglecoincide with the line on the protractor. Happy measuring!

ANGLE REVIEW

• ACUTE: LESS THAN 90 DEGREES•OBTUSE: GREATER THAN 90

DEGREES• RIGHT: 90 DEGREES

SAMPLE ACUTE ANGLES

Most Suitable for Roof Slopes

Sample Obtuse Angles

Not Suitable for Roof Slopes

RELATING ANGLES TO ROOF SLOPES

• ACUTE ANGLES ARE USED FOR ROOFS• ANGLES GREATER THAN 45 DEGREES ARE

CONSIDERED TO BE STEEP SLOPES• ANGLES BETWEEN 20-45 DEGREES ARE

TYPICAL ANGLES USED FOR ROOF SLOPES• ANGLES LESS THAN 20 DEGREES ARE

CONSIDERED TO BE LOW ROOF SLOPES

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.

A B

C

D E