In pair annihilation,an electron and a positron destroy each other to produce gamma radiation. How is the momentum conserved?

(N/A) When an electron and a positron move towards each other with equal speeds,their total momentum is $mv \hat{i} + mv(-\hat{i}) = mv \hat{i} - mv \hat{i} = \vec{0}$.
When these particles annihilate,they produce two $\gamma$-ray photons moving in opposite directions. The total momentum of these photons is $\frac{h}{\lambda} \hat{i} + \frac{h}{\lambda}(-\hat{i}) = \vec{0}$.
Thus,the total momentum remains constant before and after the annihilation process,confirming that momentum is conserved.