 formula_37

The principal stresses formula_38 and formula_39, or minimum and maximum normal stresses formula_40 and formula_41, respectively, can then be obtained by replacing both values of formula_33 into the previous equation for formula_15.This can be achieved by rearranging the equations for formula_15 and formula_16, first transposing the first term in the first equation and squaring both sides of each of the equations then adding them.Thus we have

where

which is the equation of a circle of radius formula_49 centered at a point with coordinates formula_50, called Mohr's circle.