# Q (10)  Find the values of the trigonometric functions $\small \cot \left ( -\frac{15\pi }{4} \right )$

We know that cot x repeats after an interval of $\pi or 180\degree$
$\cot \left ( -\frac{15\pi}{4} \right ) = \cot \left ( -4\pi +\frac {\pi}{4} \right ) = \cot \left ( \frac{\pi}{4} \right ) = 1$