Hello guys.

I'm really not sure what to do with this, since I'm not quite familiar with using pi or the sin,cos,tan in equations. Especially the sin,cos,tan.

Find:$\displaystyle f(\frac{\pi}{6})$

If $\displaystyle f(x) = \frac{-5\cos(9x)}{2\sin(-x)}$

A few steps on how to do this with explanation would be greatly appreciated thanks in advance!