The diagram opposite shows a sheet of material subjected to a stress of 60 N/mm. Prior to loading a square is scribed on the surface as indicated by the dotted line. If E=80 kN/mm and v = 0.3 determine the change in the lengths of the diagonals of the square and the changes in the angles at the comers of the square. 10 cm 60 N/mm2 60 N/mm2 (derinntal -0.1061 mm; &ertical -0.03182 mm; y 9.7510)