Is a function differentiable?

[floralcloud]

I am to determine if the function j(k)= tan|k| is differentiable... I tried to determine it graphically, but still wasn't sure, so I decided to try to find it algebraically, so I set it up like this

lim  =      (tan |k + h| - tan |k|)/ h =?
h ->o-

lim =       (tan |k + h| - tan |k|)/ h =?
h -> 0+

I'm not really sure how to go from there. Help would greatly be appreciated, thanks in advance!