please answer with an explanation

6.16 Consider a particle of mass m moving in three dimensions in the attractive potential V(r) = k/r with k = const. Use spherical polar coordinates (r, 9, CD). (a) Prove that the energy can be expressed in terms of the action variables as E M Mimic2 (J, + J, + J,)' (b) Discuss the frequencies of the system' (c) Use the SommerfeldWilson quantization conditions to derive the Bohr theory of the hydrogen atom