## Trigonometry (11th Edition) Clone

$\frac{\sqrt{6}-\sqrt{2}}{4}$
$cos~\frac{5\pi}{12}$ $=cos~(\frac{3\pi}{12}+\frac{2\pi}{12})$ $=cos~(\frac{\pi}{4}+\frac{\pi}{6})$ $=cos~\frac{\pi}{4}~cos~\frac{\pi}{6} - sin~\frac{\pi}{4}~sin~\frac{\pi}{6}$ $=(\frac{\sqrt{2}}{2})(\frac{\sqrt{3}}{2}) - (\frac{\sqrt{2}}{2})(\frac{1}{2})$ $=\frac{\sqrt{6}-\sqrt{2}}{4}$