Geometric considerations of the stress state
Equations 8.4a and 8.4b 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).
shear and normal stress coefficients are assumed unit!
Note: The shear stress curve should be halved. The curve shows Sin (2theta) instead of 5.*sin(2theta)