As shown in Figure 6, to determine the stress components ( σ σ n , τ τ n ) acting on a plane D at an angle θ θ counterclockwise to the plane B on which σ σ x acts, we travel an angle 2 θ θ in the same counterclockwise direction around the circle from the known stress point B ( σ σ x , − − τ τ x y ) to point D ( σ σ n , τ τ n ) , i.e., an angle 2 θ θ between lines O B ¯ ¯ and O D ¯ ¯ in the Mohr circle.