(a) Equations 6.4a and 6.4b are expressions for normal () and shear () stresses, respectively, as a...

(a) Equations 6.4a and 6.4b are expressions for normal (σ′) and shear (τ′) stresses, respectively, as a function of the applied tensile stress (σ) and the inclination angle of the plane on which these stresses are taken (θ of Figure 6.4). Make a plot on which is presented the orientation parameters of these expressions (i.e., cos2 θ and sin θ cos θ) versus θ.
(b) From this plot, at what angle of inclination is the normal stress a maximum?
(c) Also, at what inclination angle is the shear stress a maximum?