$*$Prob$.1\mathrm{.}4-6.$ A portion of the boom of a crane at a construction site is shown in Fig. P$1\mathrm{.}4-6.$ The cable from the lift motor to the cargo sling is parallel to $BE$ and $FI$ and passes over a pulley that is supported by a frictionless pin at $A.$ The weight of the sling and pallet being lifted is $W=6kN.$ Neglecting the weight of the truss members and the weight of the pulley and cable, $($a$)$ determine the axial force in each of the following members: $F_1($in member $BC),F_2($in member $($:$CF$