Complementary and Supplementary Angles
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Subject Area: Mathematics (B.E.S.T.) | Grade Level: 8
Lesson Length: 1 hour
Keywords/Tags: Angles, Complementary, Supplementary
Lesson Description: In this lesson, students will learn about the special pairs of angles and use them to solve math problems.

  • MA.8.GR.1.4 Solve mathematical problems involving the relationships between supplementary, complementary, vertical or adjacent angles.
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Video : Complementary Angles & Supplementary Angles
Instructions: Please watch the following video as often as needed before going through other lesson pages. Understanding the content of the video is very important since the lesson activities will be all about this video content.
Description: Learn about complementary and supplementary angles with Mr. J!
Reading : More about these special pairs of angles
Instructions: Please read the following notes as many times as needed (aloud and silent) before going through the rest of the lesson pages. Understanding the content of this passage is very important since the following lesson activities will be all about this content. Feel free to print the notes if needed.

Complementary angles: a pair of angles that add to equal 90 degrees.

  • When adjacent, they form a right angle.
  • If nonadjacent, they only sum to equal 90 degrees and do not form a right angle.

Supplementary angles: a pair of angles that add to equal 180 degrees.

  • When adjacent, they form a straight angle or line.
  • When nonadjacent, they only sum to equal 180 degrees and will not form a line.

Complementary and Supplementary angles must come in pairs only.

  • There must be two angles.
  • One angle cannot be complementary or supplementary.
  • One angle that measures 90 degrees is a right angle.
  • One angle that measures 180 degrees is a straight angle (or a line).
  • Three or more angles equaling 90 or 180 degrees are not said to be complementary or supplementary.

*A strategy that helps: Put these vocabulary words in ABC order and "pair" the words with 90 and 180 in numerical order.

    • Complementary is the pair of angles whose sum is 90 degrees.
    • Supplementary is the pair of angles whose sum is 180 degrees.

Quiz : Complementary and Supplementary Angles
Instructions: Please complete this quiz by choosing the correct answer for each question. You can take this quiz as many times needed.
Question #1
True or False: Complementary angles are a pair of angles that add to equal exactly 90 degrees.
Question #2

The measure of an angle is 70 degrees. What is the measure of its complement?

Question #3

Which pair of measures would form complementary angles?

Question #4
YEs or No: Complementary angles CAN make a right angle.
Question #5
Yes or No: Three angles are supplementary when they add to equal 180 degrees.
Question #6

The measure of an angle is 65 degrees. What is the measure of its supplement?

Question #7

Which pair of measures would form supplementary angles?

Question #8
True or False: Supplementary angles MUST make a straight line.
Question #9
Provide a pair of complementary angles (not used in this quiz or the video) and explain how you know.
Question #10
Provide a pair of supplementary angles (not used in this quiz or the video) and explain how you know.
Description: Self-assess your knowledge of complementary and supplementary pairs of angles!
Resources : Additional Resources
Instructions: Please see additional external resources below. Feel free visit each link to learn more about this lesson.
IXL Practice
Sign in to your student account on IXL and complete Level H, Code CC.15. Aim for a SmartScore of 80 or higher.
Quizizz Practice
Use this quizizz as extra practice for this concept. You may practice this online quiz as many times as you like.
Kuta Free Worksheet Practice
The first two pages of this PDF are the student copy without answers. The third and fourth pages of the PDF have the answers in red. Please use this resource to help you learn pairs of angles and extend your learning beyond today's lesson.
Blooket Game
Use this Blooket game in "solo" mode to identify and find complementary and supplementary angles. Choose the game type you wish to play. One is available if you need a tutorial on how each Blooket game type works.