Use virtual work method to solve for the vertical deflection at point B$,$ C and D of the truss shown below. Note:

vertical distance of point $A$ to $F$ is exactly $5$ meters while the horizontal distance between points $A$ to $B,B$ to $C,C$ to $D,$

$D$ to $F$ is $3$ meters. $A=200m{m}^2($all members has uniform cross$-$sectional area$)E=200$GPa