Supplementary Angles

Lesson Objective

In this lesson, we will learn about supplementary angles.

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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Math Video Transcript

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In this lesson, we will learn about supp. angles.

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Let's take a look at these two angles.

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Notice that, when we add these two angles, we get 180 degrees.

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When this happens, we can say that these two angles are supp. angles.

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Now, when we move this arm, note that these two angles must add up to 180 degrees, to remain as supp. angles.

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Adding 65 degrees with 115 degrees, gives 180 degrees.

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Adding 46 degrees with 134 degrees, gives 180 degrees.

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Adding 120 degrees with 60 degrees, gives 180 degrees.

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Now, let's see some examples. Are these supp. angles?

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To find out, we just need to add 50 degrees with 130 degrees. This gives 180 degrees.

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Hence, these are supp. angles.

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Next example, these two angles are supp. angles. Find x.

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Now, when we add up these 2 angles, we must get 180 degrees.

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Hence, we can find 'x', by subtracting 180 degrees, with 75 degrees.

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Therefore, we get x equals to, 105 degrees.

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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.

Question 1

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