For the arch shown in Figure P6.20, the thrust force exceeded the abutment's lateral support capacity, which is represented by a roller at \(C\). Load \(P\) was removed temporarily and tension \(\operatorname{rod} A C\) was added. If the maximum compression in members \(A B\) and \(B C\) will be 750 kips, what size diameter tension rod is required? (Ignore dead load of the arch.) The allowable tensile capacity of the rod is \(32 \mathrm{ksi}\). Determine the reactions.