Imaginary of input impedance

Zin = Rs + Ri + Rg + 1/(Wp*Cgs)

From the equation, i need to generate the Im{Zin} but i don't know how.. I only got Zin=23.61Ohm..What is make the equation will get Re{Zin} + IM{Zin}?
Cgs=0.351pF..How to generate the imaginary part from the capacitance?

What is Wp?

You should get the imaginary part from Cgs. How come frequency is missing in your equation?

I beleive wp is 2piF,
correct?

Xc=-J/(WC)