Today we use the Greek letter as to denote the ratio of the circumference of a circle to its diameter. But it was not always represented that way. At one time it was designated by the letter at other times as a ratio of single letters such as /. Presumably this last notation suggests a ratio where the designates the circumference and the designates the diameter. The ratio of the circumference to the diameter of a circle was introduced as the single letter π in a treatise examining lengths of curves.
Who introduced it?
Author: Joseph Mazur