## Trigonometry 7th Edition

$\cos(-\theta)\csc(-\theta)\tan(-\theta)=1$
$\csc(-\theta)$ can be written as $\frac{1}{\sin(-\theta)}$. $\tan(-\theta)$ can also be written as $\frac{\sin(-\theta)}{\cos(-\theta)}$. Therefore, the equation can be rewritten: $\cos(-\theta)\csc(-\theta)\tan(-\theta)=\cos(-\theta)\frac{1}{\sin(-\theta)}\frac{\sin(-\theta)}{\cos(-\theta)}=1$ As the trigonometric terms cancel out, $\cos(-\theta)\csc(-\theta)\tan(-\theta)=1$