$3\mathrm{.}74$ A wiring harness is made by routing wires around $2-$in$.-$diameter pegs mounted on a sheet of plywood. If the force in each wire is $3$ lb $,$ determine the smallest value of the distance $\backslash ($ a $\backslash )$ so that when wires $\backslash ($ A B $\backslash )$ and $\backslash ($ C D $\backslash )$ are in place the resultant couple acting on the plywood is $\backslash (159\mathrm{.}6\backslash$mathrm$\{$lb$\}\backslash$cdot $\backslash$mathrm$\{$in$\}\backslash ).$ counterclockwise.