Elementary Geometry for College Students (6th Edition)

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

Chapter 11 - Section 11.4 - Applications with Acute Triangles - Exercises - Page 520: 28

Answer

$28.6^{\circ} $

Work Step by Step

We use the Law of Cosines to find: $cos(2\alpha)= \frac{-(6^2) + 5^2 + 7^2 }{2(5)(7)} \\ cos2\alpha = .54 \\ \alpha = 28.6^{\circ} $
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