What is the Greek letter representation for the letter 'Pi'?

The representation of the letter 'Pi' in the Greek alphabet is indeed the letter that resembles a capital "P" but with an extended shape and horizontal top bar. In Greek, 'Pi' is written as Π. This letter is significant in various fields, particularly in mathematics and physics, where 'pi' refers specifically to the mathematical constant representing the ratio of a circle’s circumference to its diameter, approximately equal to 3.14159.

In contrast, the other letters listed are distinct from 'Pi.' For example, 'P' is the English alphabet representation and does not convey the same meaning as the Greek letter. The letter Σ represents the Greek letter Sigma, used to denote summation in mathematics, while 'T' represents a completely different letter in both Greek and English contexts. Thus, Π is the correct representation of 'Pi' in the Greek alphabet, aligning perfectly with its established usage in various academic and scientific disciplines.