Complementary, Supplementary, Vertical & Adjacent Angles

Complementary, Supplementary, Vertical & Adjacent Angles
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  • 0:03 Complementary Angles
  • 1:47 Supplementary Angles
  • 2:47 Vertical Angles
  • 3:44 Adjacent Angles
  • 4:21 Lesson Summary
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Lesson Transcript
Instructor: Yuanxin (Amy) Yang Alcocer

Amy has a master's degree in secondary education and has taught math at a public charter high school.

After watching this video lesson, you will know how to locate complementary, supplementary, vertical, and adjacent angles. You will understand how easy it is to visually see them. You will also know what to look for.

Complementary Angles

In this lesson, you will be learning about angles. Specifically, you will learn how to identify four different types of angles: complementary, supplementary, vertical, and adjacent. The definitions of each term will be presented as it is discussed. You need to learn about these types of angles because you will come across these terms and problems related to these types of angles on your math tests and possibly on the job in later life. If you end up with a career as an architect or an engineer, then knowing these types of angles will help you problem solve. So, let's get started.

The first is complementary angles. When a pair of angles is said to be complementary, it means that the two angles add up to 90 degrees. Yes, the two angles together form a right angle. For example, if one angle measures 40 and the angle next to it measures 50, then these two angles together are complementary to each other.


If you are asked to see if two angles are complementary, just add them up to see if they equal 90.

Sometimes, you will be asked to find an angle that is complementary to another angle. To solve this kind of problem, you need to find a number that, when added to your angle, will give you 90. This is essentially a subtraction problem. You take 90 and subtract your angle to find the other angle that when added to your angle gives you 90. So, for example, if you had a problem that asked you to find the complementary to an angle that measures 35, you would subtract 35 from 90 to find the complementary angle: 90 - 35 = 55. The complementary angle to 35 is 55.

How can you remember this? Well, since complementary angles are also right angles, perhaps you can think of complementing someone who is right.

Supplementary Angles

Okay, next comes supplementary angles. When a pair of angles is said to be supplementary, it means that the two angles add up to 180 degrees. What does a 180-degree angle look like? It looks like a straight line. It is a straight line. So, if two angles are supplementary, it means that they, together, form a straight line. For example, the two angles 115 and 65 are supplementary because they add up to 180, thus forming a straight line.


If you are asked to check whether two angles are supplementary, just check to see if they add up to 180.

If, on the other hand, you are asked to find an angle that is supplementary to another angle, you would take 180 and subtract your angle to find the angle that is supplementary. For example, to find the supplementary angle to 95, you take 180 and subtract 95 from it. You get 180 - 95 = 85. So, 85 and 95 are supplementary angles.

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