A line segment joining any two points on the circumference of a circle is called a chord of the circle. In the following figure, in circle O, line segments MN, XZ, PY and AB are the chords. Here, AB is the longest chord which passes through the center. This is called the diameter of the circle.

i) The line extension of a chord is known as secant line or just secant.
ii) Two chords are equidistant from the center only if their lengths are equal.
iii) When the chord ends are joined at the center of the circle, it forms an isosceles triangle.