The truss shown below is loaded by a dead load of PDL$=60$ kips and a live load of PLL$=30$ kips. Calculate the factored axial compression in the diagonal member A$,$ and then design a pair of double angles $(2$L $-$ long leg back$-$to$-$back, LLBB$)$ to resist the compression force. Assume: Gr$.36$ steel $($Fy $=36$ ksi, Fu $=58$ ksi$)$; that the truss is braced in the out$-$of$-$plane directions at the panel points, but that the members can buckle between panel points; gusset plates are $3/8$ thick; and that the effective buckling length of the members are equal to the length between panel points.