$Mr{m}^2$

Q$4$: The truss shown has $A=400m{m}^2$ and $E=200$GPa, Determine the horizontal displacement of joint C if a $4$ kN force is applied to the truss at C $.$ Knowing that $Ax=-4kN,Ay=-1\mathrm{.}5kN,By=1\mathrm{.}5kN.$ And internal forces at members as shown. $(25$ mark$)$

${}_{ch}=?$