For a truss with a cross-sectional area of 30cm^2 and a Young's modulus of 205 GPa, calculate the vertical displacement of the point where a vertical concentrated force of 10 kN is applied (point C). Take into account the influence of normal forces.

Dimension the section of the truss based on the allowable normal stresses f=160 MPa. Calculate the rotation angle of the bar C-E for the dimensioned section. Take into account the influence of normal forces.