Please solve this particle physics problem

1.4 Deduoe an expression for the energy of a yray from the decay of the neutral pion, 3:0 > 23/, in terms of the mass m, energy E and velocity c of the pion and the angle of emission 9 in the pion rest frame. Show that if the pion has spin zero, so that the angular disuibution is isotropic, the laboratory energy spectrum of the y-rays will be at, extending from E (1 + ,B)/2 to E (1 {ED/2. Find an expression for the disparity D (the ratio of energies) of the y-rays and show that D > 3 in half the decays and D > 7 in one quarter of them