\(A\) rigid bar \(A B C\) is hinged at \(A\) and suspended at two points \(B\) and \(C\) by two bars BD and CE made of aluminium and steel respectively as shown in Fig. 13.37. The aluminium bar is of \(6 \mathrm{~mm}\) diameter and steel bar of \(4 \mathrm{~mm}\) diameter. Calculate the stress developed in each bar. \(E_{a l}=70 \mathrm{GPa}, E_{s}=200 \mathrm{GPa}\)..