Trigonometry (11th Edition) Clone

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

Chapter 2 - Review Exercises - Page 93: 6


$\theta = 30^{\circ}$

Work Step by Step

Use the concept of cofunctions $\sin x = \cos (90^{\circ} - x)$ $\cos (\frac{3\theta}{5} + 11^{\circ}) = \sin (\frac{7\theta}{10}+40^{\circ})$ $\cos (\frac{3\theta}{5} + 11^{\circ}) = \cos (90^{\circ} -\frac{7\theta}{10} -40^{\circ})$ $\frac{3\theta}{5} + 11^{\circ} = 90^{\circ} -\frac{7\theta}{10} -40^{\circ} $ $\frac{13\theta}{10} = 39^{\circ}$ $\theta = 30^{\circ}$
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