any idea on how to solve this i have no idea where to start on these type of functions ?
limit of (4x/tanx)
x> (pie/4)
x is approaching pie over 4
It's in determinant form isn't it? You don't need to do any simplification. You can use direct substitution.
$\displaystyle \tan\left(\frac{\pi}{4}\right)=1$
$\displaystyle 4\left(\frac{\pi}{4}\right)=\pi$
So $\displaystyle \lim_{x->\frac{\pi}{4}}\frac{4x}{\tan(x)}=\pi$