4. The solid steel bar shown below has a diameter of1.72 in. The bar is subjected to a twisting torque T and a uniaxial tensile force F of the magnitudes

as shown. [a] Determine the state of stress ("stress tensor" or "stress matrix", Ơij) at point A. [b] Use the Maximum Shear Stress and Distortion Energy Theories to determine the yield strength of the material that must not experience yielding. (15 points)