Functions Modeling Change: A Preparation for Calculus, 5th Edition

Published by Wiley
ISBN 10: 1118583191
ISBN 13: 978-1-11858-319-7

Chapter 9 - Trigonometric Identities, Models, and Complex Numbers - 9.3 Sum and Difference Formulas for Sine and Cosine - Exercises and Problems for Section 9.3 - Exercises and Problems - Page 368: 10



Work Step by Step

Finding the exact value using the Laws of Trigonometry, we obtain: $$\cos \left(90^{\circ \:}-345^{\circ \:}\right) \\ \cos \left(-255^{\circ \:}\right) \\ -\frac{\sqrt{6}-\sqrt{2}}{4}$$
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