2. Consider Helmholtz equation ∇²u(r)+k²u(r) = 0 in polar coordinates (p, θ). (a) show that the radial part of Helmholtz equation is p^2 d²R(p)/ dp^2+ p dR(p)/dp + (k²p²-m²)) R(p) = 0 (b) What are the possible solutions of Eq. (3) ? Note that the case k = 0 corresponds to the Laplace equation in two dimensional polar coordinates. For m = 0 we have Laplace equation in two dimensional polar coordinates with rotational symmetry.