How to use a protractor

Written by ehow contributor
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A protractor is a tool that allows you to measure an angle or construct an angle of a given measure.

Skill level:
Easy

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Things you need

  • Protractors
  • Notebook Papers
  • Pencils And Erasers

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Instructions

  1. 1

    Find the center hole on the straight edge of the protractor.

  2. 2

    Place the hole over the vertex, or point, of the angle you wish to measure.

  3. 3

    Line up the zero on the straight edge of the protractor with one of the sides of the angle.

  4. 4

    Find the point where the second side of the angle intersects the curved edge of the protractor.

  5. 5

    Read the number that is written on the protractor at the point of intersection. This is the measure of the angle in degrees.

  1. 1

    Use the straight edge of the protractor to draw a straight line. This line will form one side of your angle.

  2. 2

    Find the center hole on the straight edge of the protractor.

  3. 3

    Place the hole over one end point of the line you have drawn.

  4. 4

    Line up the zero on the straight edge of the protractor with the line.

  5. 5

    Make a mark at the number on the curved edge of the protractor that corresponds to the desired measure of your angle. For example, mark at 90 for a 90-degree angle.

  6. 6

    Use the straight edge of the protractor to connect the mark to the end point of the first line, forming an angle.

Tips and warnings

  • There are 360 degrees in a circle.
  • A straight line measures 180 degrees.
  • The corner of a square measures 90 degrees. This is called a right angle.
  • Angles that measure fewer than 90 degrees are called acute angles. Those measuring more than 90 degrees are called obtuse angles.

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