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Nuclear physics: particle interactions

Hi, pls help me solve this qn:

(c) The kinetic energy of the positron is 1.58 MeV. It annihilates with a stationary electron and two photons of equal energy are emitted.

Calculate the wavelength of the emitted photons.

mass of stationary electron = 0.511MeV / (c ^ 2)

mass of stationary positron = 0.511MeV / (c ^ 2)
Convert ke into joules.
Convert both masses into energy, E = mc^2.
Add up for total energy.
Divide by 2, convert into wavelength using hc /E

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