Home Work $2\mathrm{.}4.$

$2\mathrm{.}4.$ Two gondolas on a ski lift are locked in the position shown in the figure while repairs are being made elsewhere. The distance between support towers is $L=100ft.$ The length of each cable segment under gondola weights $W_B=450lb$ and $W_C=650lb$ are $D_{AB}=12ft,D_{BC}=70ft,$ and $D_{CD}=20ft.$ The cable sag at $B$ is $B=3\mathrm{.}9ft$ and that at $C,C=7\mathrm{.}1ft.$ The effective cross$-$sectional area of the cable is $A_e=0\mathrm{.}12$ in ${?}^2.$

$($a$)$ Find the tension force in each cable segment; neglect the mass of the cable.

$($b$)$ Find the average stress in each cable segment.