What if you notice two angles in a picture that make a straight line? What information does this give you about the angles? After completing this Concept, you'll be able to apply the properties of linear pairs to help you solve problems.
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CK12 Foundation: Chapter1Linear PairsA
Guidance
Adjacent angles are two angles that have the same vertex, share a side, and do not overlap. In the picture below,
A linear pair is two angles that are adjacent and whose noncommon sides form a straight line. If two angles are a linear pair, then they are supplementary.
Example A
What is the value of each angle?
These two angles are a linear pair, so they are supplementary, or add up to
So, plug in
Example B
Are
The two angles are not a linear pair because they do not have the same vertex. However, they are supplementary,
Example C
Name one linear pair in the diagram below.
One example is
Watch this video for help with the Examples above.
CK12 Foundation: Chapter1LinearPairsB
Vocabulary
Adjacent angles are two angles that have the same vertex, share a side, and do not overlap. A linear pair is two angles that are adjacent and whose noncommon sides form a straight line. If two angles are a linear pair, then they are supplementary.
Guided Practice
1. What is
2. What is
3. If
Answers:
1.
2.
3.
Interactive Practice
Explore More
For 15, determine if the statement is true or false.
 Linear pairs are congruent.
 Adjacent angles share a vertex.
 Adjacent angles overlap.
 Linear pairs are supplementary.
 Supplementary angles form linear pairs.
Find the measure of an angle that forms a linear pair with

54∘ 
32∘ 
104∘ 
71∘ 
149∘ 
x∘
For 1216, find the value of