Problem $4\mathrm{.}18$: Cable AB on the boom truck is hoisting the $2500$ lb section of precast concrete $($Figure P$4\mathrm{.}18).$ A second cable is under tension P$,$ and workers use it to pull and adjust the position of the concrete section as it is being raised. Figure P$4\mathrm{.}18$

$($a$)$Draw a free body diagram of hook A$,$ treating it as a particle.

$($b$)$Determine P and the tension in cable AB$.$