#### Answer

$-\cos \theta $

#### Work Step by Step

$\cos \left( 180-\theta \right) =\cos {180}\cos \theta +\sin {180}\sin \theta =-1\times \cos \theta +0\times \sin \theta =-\cos \theta $

Published by
Pearson

ISBN 10:
013421742X

ISBN 13:
978-0-13421-742-0

$-\cos \theta $

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