Consider two thin rods as shown in the figure, which are pinned at $A,B,$ and C and are initialy horizontal and of length $L$ when no load is applied. The weight of each rod is negligible. A force Q is then applied $($gradually$)$ at point B$.$

A$.$ Determine the magnitude of $Q$ to produce a prescribed vertical deflection d at point B$.$

B$.$ Let us consider rods each of initial length $2$ m and cross$-$sectional area $0\mathrm{.}6c{m}^2.$ For a load Q of $85$ N determine the central deflection $$ by both the exact and the approximate relations. Use $E=200$

$($a$)$

GPa.