$!$

Required information

A $2-$kip$-$ft torque is applied to a hollow aluminum shaft having the cross section shown. Assume $p=4$ in$,q=6$ in$.,r=0\mathrm{.}08$ in and $s=0\mathrm{.}1$ in$.$ Neglecting the effect of stress concentrations, determine the shearing stress at points a and $b.$

Using average dimensions, the enclosed area is

in $($:${?}^2$