Secant line 3-secants of a finite set of points. Finiteness of the set of points is not essential in this definition, as long as each line can intersect the set in only a finite number of points. Secant line In geometry, a secant of a curve is a line that intersects the curve in at least two (distinct) points. The word "secant" comes from the Latin word "secare", meaning "to cut". In the case of a circle, a secant will intersect the circle in exactly two points and a chord is the line segment determined by these two points, that is the
Curvature of a measure points "x", "y" and "z" in R, let "R"("x", "y", "z") be the radius of the Euclidean circle that joins all three of them, or +∞ if they are collinear. The Menger curvature "c"("x", "y", "z") is defined to be with the natural convention that "c"("x", "y", "z") = 0 if "x", "y" and "z" are collinear. It is also conventional to extend this definition by setting "c"("x", "y", "z") = 0 if any of the points "x", "y" and "z" coincide. The Menger-Melnikov curvature "c"("μ") of "μ" is defined to be More generally, for "α" ≥ 0, define "c"("μ")