Trigonometry (10th Edition)

Published by Pearson
ISBN 10: 0321671775
ISBN 13: 978-0-32167-177-6

Chapter 3 - Radian Measure and the Unit Circle - Section 3.3 The Unit Circle and Circular Functions - 3.3 Exercises - Page 119: 85e

Answer

$86^{\circ}$

Work Step by Step

Since August represents $x=7$, we substitute $x=7$ in the equation, $t=60−30\cos(\frac{\pi}{6}x)$ $t=60−30\cos(\frac{\pi}{6}\times7)$ $t=60−30\cos(\frac{7\pi}{6})$ $t=60−30(-\frac{\sqrt 3}{2})$ $t=60-15(-\sqrt 3)$ $t=60+25.98$ $t=85.98\approx86^{\circ}$
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