PROBLEM $1\mathrm{.}40$

Members $AB$ and $BC$ of the truss shown are made of the same alloy. It is known

that a $20-mm-$square bar of the same alloy was tested to failure and that an

ultimate load of $120$ kN was recorded. If a factor of safety of $3\mathrm{.}2$ is to be

achieved for both bars, determine the required cross$-$sectional area of $($a$)$ bar

$AB,(b)$ bar $AC.$

The answers are $(a)181\mathrm{.}3m{m}^2$ and $(b)213m{m}^2$

Please include Free Body Diagram