$7\mathrm{.}88$ A transmission cable weighs $0\mathrm{.}3l\frac{b}{f}t$ and has a

maximum allowable tension of $1500lb.$ It is to be strung

between two towers that are $2450ft$ apart, horizontally,

and at elevations of $7200ft$ and $6500ft,$ respectively $($see

Fig. P$7\mathrm{.}88).$ Determine the minimum length of cable

needed.

The answer is: L$=2580$