$3-$ The rods $1,2,$ and $3$ shown below are welded together, mounted between two rigid walls and subjected to the two forces shown at joints $B$ and $C.$ Rods $1$ and $3$ are of the same length, $L_1=L_3=1\mathrm{.}2m$ and $L_2=1\mathrm{.}5m.$ Rods $1$ and $3$ are made from a material with $E=50$ GPa $.$ Rod $2$ is made from a material with $E=30$GPa. The cross sections are given by: $A_1=A_3=0\mathrm{.}01m^2$ and $A_2=0\mathrm{.}025m^2.$ Determine the displacements of joints $B$ and $C.$