1. The problem statement, all variables and given/known data why the strain of εxy , εxz , εyx , εzx , εyz , εzy is γ_xy / 2 , γ_xz / 2, γ_yx / 2, γ_zx / 2 , γ_yz / 2 , and γ_zy / 2 ??? how to get that ?. 2. Relevant equations 3. The attempt at a solution Taking an example of εxy , what does γ_xy / 2 mean ?