CK-12 Geometry-Concepts

3.4. Alternate Interior Angles http://www.ck12.org

3. List the pairs of alternate interior angles:

Answers:

1. First, findm^6 1. We know its linear pair is 109◦. By the Linear Pair Postulate, these two angles add up to 180◦, so
   m^61 = 180 ◦− 109 ◦= 71 ◦. This means thatl||m, by the Converse of the Corresponding Angles Postulate.


2. Because these are alternate interior angles, they must be equal fora||b. Set the expressions equal to each other
   and solve.

3 x+ 16 ◦= 5 x− 54 ◦

70 ◦= 2 x

35 ◦=x To makea||b,x= 35 ◦.

3. Alternate Interior Angles:^6 4 and^6 5,^6 3 and^6 6.

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1. Is the angle pair^6 6 and^6 3 congruent, supplementary or neither?


2. Give two examples of alternate interior angles in the diagram: