How Do You Prove Thermodynamic Equations for Van der Waals Gas?

[Outrageous]

Homework Statement

The question c) I have attached. Capture th.PNG (27.7 KB)
Capture th2.PNG (14.8 KB)

Homework Equations

The Attempt at a Solution

Use U=f(T,V) and H=f(T,P), then get Cp and Cv, so I can get gamma.
then k=(1/v)(dv/dt)
but I still can't prove it.

 

[haruspex]

There must be some relevant equations you're allowed to use. How about some of those here: http://en.wikipedia.org/wiki/Van_der_waals_gas ?