Elementary Geometry for College Students (6th Edition)

Published by Brooks Cole
ISBN 10: 9781285195698
ISBN 13: 978-1-28519-569-8

Chapter 4 - Section 4.1 - Properties of a Parallelogram - Exercises - Page 178: 36b


Equilateral triangle

Work Step by Step

$\angle$ADE=$\frac{1}{2}$$\angle$D $\angle$A+$\angle$D=180 $\angle$A+$\angle$ADE+$\angle$AED=180 $\angle$A+$\frac{1}{2}$$\angle$D+$\angle$AED=180 $\angle$A+$\frac{1}{2}$$\angle$D+$\angle$AED=$\angle$A+$\angle$D $\angle$AED=$\frac{1}{2}$$\angle$D Since two angles have a measure equal to half of angle D, it must be an equilateral triangle.
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