Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 5 - Section 5.3 - Trigonometric Graphs - 5.3 Exercises - Page 430: 77

Answer

Solutions: x=1.16

Work Step by Step

Using a graphing calculator to graph the function cos(x) = 0.4, and inputting lines x = 0 and x = $\pi$ to establish the interval of interest, we see that the only solution (x-intercept of cos(x) = 0.4) within the interval is x $\approx$ 1.159279. As the question wants the solution rounded to 2 decimal places, the solution is 1.16.
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