Assignment:
An electron-positron pair moves with velocity v=c(beta) in frame O. Annihilation of the pair produces two photons of energies E1 and E2 emerging at angles theta(1) and theta(2), with respect to the velocity (v). Find expressions for the energies E1 and E2 in terms of the electron mass, the speed (beta) and angle theta(1).
Provide complete and step by step solution for the question, use formulas.