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

    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.

    example of  Linear Pair
    Choices:
    A. 148
    B. 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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