4. Show that 1 (1 - 22 - y)yo u(r,() = - arctan where arctant (0,7) T (x - 1)2 + (y yo)? y is the solution to Dirichlet's problem for the unit disk for the piecewise continuous function (1 if (0,20) h(ei) = 0 if (20., 21) where 0o (0,7/2) and yo = tan 06. Check that u(r, ) has the correct behaviour at the boundary. 4. Show that 1 (1 - 22 - y)yo u(r,() = - arctan where arctant (0,7) T (x - 1)2 + (y yo)? y is the solution to Dirichlet's problem for the unit disk for the piecewise continuous function (1 if (0,20) h(ei) = 0 if (20., 21) where 0o (0,7/2) and yo = tan 06. Check that u(r, ) has the correct behaviour at the boundary