Trigonometry (11th Edition) Clone

Published by Pearson
ISBN 10: 978-0-13-421743-7
ISBN 13: 978-0-13421-743-7

Chapter 2 - Acute Angles and Right Triangles - Section 2.1 Trigonometric Functions of Acute Angles - 2.1 Exercises - Page 54: 38


$\theta$ = 15$^{\circ}$

Work Step by Step

$\cos$(2$\theta$ + 50$^{\circ}$) = $\sin$(2$\theta$ - 20$^{\circ}$) $\cos$ and $\sin$ are cofunctions if the sum of the angles is 90$^{\circ}$ Therefore: (2$\theta$ + 50$^{\circ}$) + (2$\theta$ - 20$^{\circ}$) = 90$^{\circ}$ 4$\theta$ + 30$^{\circ}$ = 90$^{\circ}$ 4$\theta$ = 60$^{\circ}$ $\theta$ = 15$^{\circ}$
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