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# 3 Easy Steps for Answering What are Complementary Angles?

Get the free Complementary Angles worksheet and other resources for teaching & understanding what are Complementary Angles

## Here’s how to find Complementary Angles

Complementary Angles are made of up two angles whose sum is 90 degrees. This means that when two angles are added together and their sum is 90 degrees then they are Complementary Angles. You can find out if angles are Complementary Angles by using addition or subtraction. When determining which angles what are Complementary Angles, you subtract to get any missing angles measure. For example, if you know one angle measure is 60 degrees and you need to find out the second angle measure, you can do 90 degrees subtracted by 60 degrees to get the remaining angle measure.

Common Core Standard: 7.G.5
Return To: Home, 7th Grade

## The Complete Complementary Angles Definition

So what is a complementary angle anyway? When two angles add up to 90 degrees they are called Complementary Angles. You can tell whether or not angles are are Complementary Angles by utilizing subtraction or addition. To answer how to find Complementary Angles, you subtract to get any missing angle measure. For instance, in the event that you realize one angle measure is 25 degrees and you have to discover the second angle measure, you do 90 degrees subtracted by 25 degrees to get the last angle measure of 65 degrees.

## 3 Steps to easily answer any Complementary Angles Example Problem

1. Complementary Angles are two angles that add up to 90 degrees.
2. If you know one angle measure, you subtract it from 90 degrees to get the other angle measure.
3. You can check to make sure the angles are Complementary Angles by making sure they are Right Angles.

## Finding Complementary Angles Practice Problems Quiz

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Complementary Angles Quiz

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Find the value of x.

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Find the value of x.

3 / 5

Find the value of x.

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Find the value of x.

5 / 5

Find the value of x.

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## Watch the video explanation of our Complementary Angles Worksheet

Watch our free video on Complementary Angles definition. This video shows how to solve problems that are on our free Complementary Angles worksheets that you can get by submitting your email above.

Watch the free Complementary Angles video on YouTube here: Complementary Angles Definition Video

Video Transcript:

This video is about answering the question what are complementary angles. You can get the 7th grade complementary angles worksheet used in this video for free by clicking on the link in the description below.

How do you answer what is complementary angles? Complementary angles are two angles that when added together will add up to 90 degrees. A 90 degree angle is also referred to as a right angle. It is always shown by a square at the junction of two rays that form an angle. In order to solve for complementary angles, you have to take the angle that you know, in this case let’s say this angle is 30 degrees, and we don’t know this angle. You take the angle that you know, which is 30 degrees, and because the two angles added together have to add up to 90 degrees, all you do is you take 90 degrees subtracted by the angle that you know, which is 30 in this case to get your solution. The angle that we’re missing in this example has to be 60 degrees because the two angles added together have to add up to 90. This would have to be 60.

Now we’re going to do a couple practice problems on our complementary angle worksheet. Let’s jump to number two on our complementary angles worksheet. We already know that complementary angles definition is that when two angles added together add up to 90 degrees. But how to solve complementary angles? We can see that this red square at the bottom means that the two angles make a right angle or an angle that’s 90 degrees. We know that this angle right here is 27 degrees but we do not know this angle but we do know that both of these angles have to add up to 90 degrees. We take our 90 degrees, because both of them have to add up to 90, and we’re going to subtract it by the angle we know which in this case is 27 degrees. When you subtract those two you will get 63 degrees which is going to be our answer. Because we know this is 27 and the two together have to be 90 the only option for this angle is that it’s 63 degrees.

Let’s move on to number four on the complementary angles problems worksheet. Now number four gives us another right angle which automatically means that they’re complementary because we know the complementary angles definition is two angles that add up to 90 degrees. What we can do is we can take the angle that we know which is 40 degrees and we can subtract it from 90. We know the whole thing has to be 90 degrees and we know this part right here is 40 degrees so we’re going to subtract it. Then we do 90 degrees minus 40 degrees and we get 50 degrees. So, this angle must be 50 degrees because the two angles together have to add up to 90.

The last problem that we’re going to do on our complementary angles worksheet is number five. Again, complementary angles definition as two angles that add up to 90 degrees. In the case of number five we know one angle has to be 25 degrees but we don’t know the other angle. That’s what we’re going to figure out. If the two added up have to equal 90 that means that we can subtract 25 from 90 and when you subtract 25 from 90 you will get 65 degrees. So we know that this angle must be 65 degrees.

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