Using a Protractor (Measuring Angles)

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Lesson Objective
In this lesson, we will learn how to measure angles using a protractor.
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About This Lesson
In this lesson, we will:
  1. Learn what is a protractor. The following picture shows the parts of a protractor.

    parts of a protractor
  2. Learn how to use a protractor to measure angles that are:

    1. Less than 180° (1st math video)
    2. Greater than 180° (2nd math video)
The study tips and math videos below will explain more.

Study Tips

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Tip #1
It is important to ensure the following when using a protractor:  
  1. The protractor's origin is at the vertex of an angle.

    origin & the vertex of the angle
  2. The protractor's base line is along the arm.

    the base line is along the arm
  3. Make sure that you are using the appropriate scale when reading the angle. For example, the angle below is 50° and not 130°:

    using the appropriate scale
The math videos below will explain more on this.

Math Video

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Video on parts of a protractor & measuring angles that are <180°
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Video on measuring angles that are >180° using a protractor
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Math Video Transcript

Practice Questions & More

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Multiple Choice Questions (MCQ)
Now, let's try some MCQ questions to understand this lesson better.

You can start by going through the series of questions on using a protractor or pick your choice of question below.
  1. Question 1 on measuring an angle that is lesser than 180°
  2. Question 2 on measuring an angle that is greater than 180°
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