A chord of a curve is a geometric line segment whose endpoints both lie on the curve.
A secant or a secant line is the line extension of a chord.
Chords of a circle
Chords of a circle have a few known properties. Here's an incomplete list:
- Chords are equidistant from the center if and only if their lengths are equal.
- A chord's perpendicular bisector passes the center.
- Given chord AB, chord CD, and intersection point P of the line extensions (secant lines) of them, the following about lengths is true: AP·PB = CP·PD (Power of a point theorem )