Protractors and Angles Lesson Topic Index | Grade 5 Math | Intermediate Test Prep | StudyZone
 A protractor is a clear plastic device used to measure angles from 0 to 180 degrees.
 There are two sets of numbers on a protractor, so you can measure angles from either side of the protractor.

 Steps to using a protractor 1. Look at the angle you are measuring. 2.  If the angles are greater than 90 degrees (an obtuse angle) use the scale that is greater than 90. 3.  If the angles are less than 90 degrees (an acute angle) use the scale that is less than 90. 4.  Place the protractor on the angle so that the center point is on the vertex and the zero line is along one side of the angle. 5. Follow the scale beginning at zero and find the number where the other side of the angle intersects the scale on the protractor. 6.  The number where the line intersects is the degree of the angle.

 Example One: Right Angle A right angle measures actually 90 degrees.

 Example Two: Obtuse Angle An obtuse angle measures greater than 90 degrees.

 Example Three: Acute Angle An acute angle measures less than 90 degrees.

 Remember: A protractor is a clear plastic device used to measure angles from 0 to 180 degrees.

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