$12\mathrm{.}3$ For a dry sand specimen in a direct shear test box, the following are given:

Size of specimen: $2\mathrm{.}8$ in$.2\mathrm{.}8$ in$.1\mathrm{.}25$ in$.($height$)$

Angle of friction: $41$

Normal stress: $22l\frac{b}{i}n.{?}^2$