Algebra and Trigonometry 10th Edition

Published by Cengage Learning
ISBN 10: 9781337271172
ISBN 13: 978-1-33727-117-2

Chapter 8 - 8.4 - Vectors and Dot Products - 8.4 Exercises - Page 595: 35



Work Step by Step

$\theta=cos^{-1}\frac{u\cdot v}{|u||v|}=cos^{-1}\frac{(-6i-3j)(-8i+4j)}{\sqrt {(-6i-3j)(-6i-3j)}\sqrt {(-8i+4j)(-8i+4j)}}=cos^{-1}\frac{48-12}{\sqrt {36+9}\sqrt {64+16}}=cos^{-1}(\frac{36}{\sqrt {3600}})=cos^{-1}0.6$ $\theta=53.13°$
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