Linear Pair
Definition of Linear Pair
Linear Pair is a pair of adjacent angles that form a straight line.
More About Linear Pair
 The sum of the measure of the angles in a linear pair is supplementary or 180�.
 If one angle of a linear pair is acute (below 90o), then the other angle is obtuse (above 90o).
Example of Linear Pair

In the above figure, ?1 and ?2, ?2 and ?3, ?3 and ?4, and ?4 and ?1 are linear pairs, as any pair of these angles forms a straight line.
Video Examples: Linear Pairs and Vertical Angles
Solved Example on Linear Pair
Ques: If m?CAB = 32, then find the m?CAD in the figure shown.
Choices:
A. 148B. 212
C. 158
D. 32
Correct Answer: A
Solution:

Step 1: If ?DAB is a straight angle, then m?CAD + m?CAB = 180 [Angle Addition Postulate.]
Step 2: m?CAD + 32� = 180� [Substitute.]
Step 3: m?CAD = 148 [Simplify.]
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