[a] (i) Show that for a solid circular shaft, the shear stress is given by Eq. 2.1: =JTR Where: T= Torque. R= Radius of the shaft. J = Polar second moment of area. [b] Draw an annotated diagram each of shear stress distribution on a cross-section of a twisted circular shaft showing: (i) Elastic region with yield stress at surface. (ii) Elastic-plastic boundary. [c] Fig Q2.1 shows a stepped shaft having fillet radius r. Given that the applied torque is 450Nm, the large and small diameters D and d are 80mm and 40mm, respectively. Calculate the maximum shear stress in the shaft for: (i) 5mm fillet radius. (ii) 8mm fillet radius