Problem $2.$ Rigid bar $BCD$ in Fig. P$3\mathrm{.}23$ is supported by a pin at $C$ and by aluminum rod $(1).$ A concentrated load $P$ is applied to the lower end of aluminum rod $(2),$ which is attached to the rigid bar at $D.$ The cross$-$sectional area of each rod is $A=0\mathrm{.}20$ in$.{?}^2$ and the elastic modulus of the aluminum material is $E=10,000$ksi. After the load $P$ is applied at $E,$ the strain in rod$(1)$ is measured as $900($tension$).$

$($a$)$ Determine the magnitude of load $P.$