Precalculus (6th Edition)

Published by Pearson
ISBN 10: 013421742X
ISBN 13: 978-0-13421-742-0

Chapter 7 - Trigonometric Identities and Equations - 7.3 Sum and Difference Identities - 7.3 Exercises - Page 679: 42


$-\dfrac {\sqrt {2}}{4}\left( \sqrt {3}+1\right) $

Work Step by Step

$\sin \left( 255\right) =\sin \left( 225+30\right) =\sin {225}\cos 30+\cos 225\sin 30=-\dfrac {\sqrt {2}}{2}\dfrac {\sqrt {3}}{2}-\dfrac {\sqrt {2}}{2}\dfrac {1}{2}=-\dfrac {\sqrt {2}}{4}\left( \sqrt {3}+1\right) $
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