Supplementary Angles
Lesson Objective
In this lesson, we will learn about supplementary angles.
About This Lesson
In this lesson, we will learn:
 What are supplementary angles.
 See some examples on identifying them.
The study tips below will give you a short summary on this.
The math video below will explain in depth about this. Furthermore, it will show some examples so that you can understand this lesson better.
Study Tips
Tip #1
When we add two angles and get exactly 180°, we can say that these angles are supplementary angles. See an example below:
The math video below will explain more on this.
Math Video
Lesson Video
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Supplementary Angles from MathExpression.com on Vimeo.

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00:00:03.220
In this lesson, we will learn about supp. angles.
00:00:09.060
Let's take a look at these two angles.
00:00:13.120
Notice that, when we add these two angles, we get 180 degrees.
00:00:20.120
When this happens, we can say that these two angles are supp. angles.
00:00:26.240
Now, when we move this arm, note that these two angles must add up to 180 degrees, to remain as supp. angles.
00:00:42.200
Adding 65 degrees with 115 degrees, gives 180 degrees.
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Adding 46 degrees with 134 degrees, gives 180 degrees.
00:01:08.210
Adding 120 degrees with 60 degrees, gives 180 degrees.
00:01:17.030
Now, let's see some examples. Are these supp. angles?
00:01:25.060
To find out, we just need to add 50 degrees with 130 degrees. This gives 180 degrees.
00:01:35.090
Hence, these are supp. angles.
00:01:41.100
Next example, these two angles are supp. angles. Find x.
00:01:49.050
Now, when we add up these 2 angles, we must get 180 degrees.
00:01:56.180
Hence, we can find 'x', by subtracting 180 degrees, with 75 degrees.
00:02:04.120
Therefore, we get x equals to, 105 degrees.
00:02:11.000
That is all for this lesson.
Practice Questions & More
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 supplementary angles or pick your choice of question below.
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