A rigid block of mass M is supported by three symmetrically spaced rods. Each copper rod has an area of 900 mm²; E = 120 GPa; and the allowable stress is 70 MPa. The steel rod has an area of 1200 mm²; E = 200 GPa; and the allowable stress is 140 MPa. Determine the largest mass M which can be supported without exceeding allowable stresses. M Copper 160 mm Steel 240 mm Copper 160 mm