As mentioned before, after the two-dimensional stress analysis has been performed we know the stress components σ σ x , σ σ y , and τ τ x y at a material point P . These stress components act in two perpendicular planes A and B passing through P as shown in Figure 5 and 6. The Mohr circle is used to find the stress components σ σ n and τ τ n , i.e., coordinates of any point D on the circle, acting on any other plane D passing through P making an angle θ θ with the plane B . For this, two approaches can be used: the double angle, and the Pole or origin of planes.