Answer
$\cos(-\theta)\tan(\theta)=\sin(\theta)$
Work Step by Step
$\tan(\theta)=\frac{\sin(\theta)}{\cos(\theta)}$
Since cosine is an even function, $\cos(-\theta)=\cos(\theta)$.
These can be substituted back into the original equation:
$\cos(-\theta)\tan(\theta)=\cos(\theta)\frac{\sin(\theta)}{\cos(\theta)}=\sin(\theta)$
Therefore the identity is true.
