P$2\mathrm{.}13$ A thin triangular plate $PQR$ forms a right angle at point $Q.$ During deformation, point $Q$ moves to the left by $u=2\mathrm{.}0mm$ and upward by $v=5\mathrm{.}0mm$ to new position $Q,$ as shown in Figure P$2\mathrm{.}13.$ Determine the shear strain $$ at comer $Q^{\text{'}}$ after deformation. Use $c=700mm,=28,$ and $=62.$