Secant line point a "tangent line" and in no points an "exterior line". A "chord" of a circle is the line segment that joins two distinct points of the circle. A chord is therefore contained in a unique secant line and each secant line determines a unique chord. In rigorous modern treatments of plane geometry, results that seem obvious and were assumed (without statement) by Euclid in his treatment, are usually proved. For instance, "Theorem (Elementary Circular Continuity)": If formula_1 is a circle and formula_2 a line that contains a point that is inside formula_1 and a point that is outside of
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,