Ex$-1$ A loaded two$-$member steel structure with two element, one inclined downward at $30$ degrees and the other downward at $60$ degrees to the horizontal with load P suspended at their connection at $1$m below from horizontal base. The yield stress of steel is $400$ MPa and the

Young's Modulus is $210$ GPa $.$ By using the unit dummy displacement method,

$($a$)$ Find the displacements at the point of application of load P

$($b$)$ Find the member strains and forces in terms of P$.$

$($c$)$ Determine the maximum possible value of P$.$