Power of a point P intersects the circle at A and B, the endpoints of the diameter. Their respective products of distances are equal to each other and to the power of point P in that circle This equality is sometimes known as the ""secant-tangent theorem"", ""intersecting chords theorem"", or the ""power-of-a-point theorem"". The power of a point is used in many geometrical definitions and proofs. For example, the radical axis of two given circles is the straight line consisting of points that have equal power to both circles. For each point on this line, there is a unique circle centered on that point
Mohr's circle stress formula_95 is the abscissa of the centre formula_85, given by and the length of the radius formula_98 of the circle (based on the equation of a circle passing through two points), is given by The maximum and minimum shear stresses correspond to the ordinates of the highest and lowest points on the circle, respectively. These points are located at the intersection of the circle with the vertical line passing through the center of the circle, formula_85. Thus, the magnitude of the maximum and minimum shear stresses are equal to the value of the circle's radius formula_98 As mentioned before,