Hi,
Well for example with R=2, C=10uf,L=1mH, and f=50Hz, we get:
Z=1.999921+0.3015934*j
which as i mentioned earlier this is a complex impedance.
But if you want to figure out the output with a current that is triangular, then we have to do a time domain analysis. But you also have to specify where your output is taken from...probably across the capacitor right?
Also, it might be better if you specify what the voltage is rather than the current. The voltage is probably pulsed right and so that makes it a little easier too. The current isnt really triangular in that case. It's close to a triangle, but not exactly.
So you next have to specify if you would rather analyze the voltage across the cap (the output presumably) with a pulsed input voltage, or you have to specify some other type of analysis but try to be specific so that we dont have to keep asking you more questions about it. The more specific you are the faster we can get you an answer
Also it might help if you specify some typical values for R, L, and C, and the voltage pulse amplitude.