On Mohr's circle for stress the maximum principal stress is shown by point 20. () . (b) . (c) C. (d) D. A plane element in a body is subjected to a normal tensile stress in the r-direction of 84 MPa, as well as shear stresses of 28 MPa, as shown. 21. 28 MPa 84 MPa 84 MPa 28 MPa Most nearly, what are the principal stresses? (A) 70 MPa; 14 MPa (B) 84 MPa; 28 MPa (C) 92 MP; -8.5 MP (D) 112 MPa; 28 P