## Calculus 8th Edition

Differentiate $y=\sin \theta \cos \theta$ $y'=\cos 2\theta$
Differentiate using product and trig rules. $y' = \sin \theta ' \cos \theta + \sin \theta \cos \theta '$ $=\cos ^2 \theta - \sin ^2 \theta$ Simplify using trig identities. = $\cos 2\theta$