Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 10 - Geometry - Chapter Summary, Review, and Test - Review Exercises - Page 680: 12


$m\angle{1} = 110^o \\m\angle{2} = 70^o \\m\angle{3} = 110^o$

Work Step by Step

RECALL: (1) Vertical angles have equal measurements. (2) Supplementary angles have a sum of 180 degrees. The 70-degree angle and angle 2 are vertical angles, so they have the same measurement. Thus, $m\angle{2} = 70^o$. Angles 1 and 2 are supplementary, so their sum is 180 degrees. Thus, $m\angle{1}= 180^o- m\angle{2}=(180-70)^o=110^o$ Angles 1 and 3 are vertical angles, so they have equal measurements. Thus, $m\angle{3} = 110^o$.
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