Hey I have been given the below question but am really struggling to get it still I understand how to solve problems using seperation of variables but this has got me stumped

We want to find the value of the electrostatic potential

in the quadrant.

,

where

and

are the standard polar co-ordinates and

is a given positive real number. Assuming electrostatic potential is the solution of Laplaces equation in polar co-ordinates

The boundary conditions on

are

(a) show that the function

is a solution of the initial equation that satisfies the first set of boundary conditions

Any help would be great

Thanks