$(6)$ A solid circular shaft is composed of two segments and loaded as shown. Determine the maximum shear stress in $($a$)$ segment AB$,$ and $($b$)$ segment BC$.$ G$\_($br$)=6*10^(6)$psi and G$\_($st $)=11*10^(6)$psi$.$ The answers should be a$)8\mathrm{.}78$ksi and b$)4\mathrm{.}26$ ksi