How can I graph following function?

Z=( ZL + j*25*(2*pi*x/0.3)) / (25 + j*ZL*tan(2*pi*x/0.3))

ZL and x are variables and we need to compute;

a) ZL=0
b) ZL=infinite
c) ZL=-j50 Ω
d) ZL=50 Ω

where x is the length of the graph.