A solid circular shaft of diameter 3 inches has a shear strain at a section in polar coordinates that was found to be x=0.002, where is the radial coordinate measured in inches. The shaft is made from elastic-perfectly plastic material that has a yield stress of yield=18ksi and a shear modulus G=12,000ksi. (a) Write expressions for x as a function of and plot the shear strain x and shear stress x distribution across the cross section. (b) Determine the equivalent internal torque acting at the cross