Linear Pair
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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 90°), then the other angle is obtuse (above 90°).
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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