Algebra 2 (1st Edition)

Published by McDougal Littell
ISBN 10: 0618595414
ISBN 13: 978-0-61859-541-9

Chapter 13, Trigonometric Ratios and Functions - 13.3 Evaluate Trigonometric Functions of Any Angle - 13.3 Exercises - Skill Practice - Page 870: 2

Answer

See below for the answer.

Work Step by Step

Since the Trigonometric function Cosine is negative in the third quadrant, when we take the cosine of the reference angle, then we make it negative.
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