Why is pi pi? Why not another letter?

Question

Well, title. Who chose the letter? I was thinking ancient Greeks (Euclidean? Pythagoras?) or was it chosen later on? Why did it stick and was not replaced like so many others?

In: 3

Answer 1

The adoption of Pi as symbol is relatively recent.
Like 18th century recent.
Pi is basically the greek letter for ‘p’ and it was used in reference to “perimeter” or “periphery”