Elementary Geometry for College Students (6th Edition)

Published by Brooks Cole
ISBN 10:
ISBN 13:

Chapter 11 - Section 11.4 - Applications with Acute Triangles - Exercises - Page 520: 26

Answer

x$\approx$ 6.5

Work Step by Step

using theorem 11.4.3 Law of cosine $x^{2}$ = $(10)^{2}$ + $(9)^{2}$ - 2*10*9*cos 40° as we know cos 40° = 0.7660 $x^{2}$ = 100+81 - 180 * 0.7660 $x^{2}$ = 181 -180 * 0.7660 $x^{2}$ = 43.12 x = $\sqrt 43.12$ x$\approx$ 6.5
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