$20\%$

$5.$a$.$ Determine the moment of inertia of the cross$-$section area of the beam about the $x$ axis.

$5.$b$.$ The simply supported beam in the below Figure has the cross$-$sectional area shown in the above Figure. Determine the maximum moment and the absolute maximum bending stress in the middle of the beam. At this location, $P=12KN$ and $L=1\mathrm{.}2m.$ Hint: ${}_{\text{m}\text{a}\text{x}}=\frac{Mc}{\text{I}},$ where c is half the height of the beam from the neutral axis.