Problem $3-1$ The horizontal rigid beam ABCD is supported

by vertical bars $BE$ and $CF$ and is loaded by vertical forces

$P_1=360kN$ and $P_2=200kN$ acting at points A and $D,$

respectively $($see figure$).$ Bars $BE$ and $CF$ are made of steel

$(E=200$GPa $)$ and have cross$-$sectional areas $A_{BE}=12,000m{m}^2$

and $A_{CF}=7,000m{m}^2.$ The distances between various points on

the bars are shown in the figure.

Determine the vertical displacements ${}_A$ and ${}_D$ of points $A$

and $D,$ respectively.