A bakelite plate (see Fig. 2) with an elliptical hole is being examined to ßnd the stress concentration factor. It is in a state of plane stress. By a method called photoelasticity, we can measure stress »yy at A at the edge of the ellipse to be 21 MPa. Find the strain values at A with reference to the x y axes. Take E = 35 GPa and · = 0.2.