Pi

${\displaystyle \pi }$ (π) (/paɪ/) is a mathematical constant that is the ratio of a circle's circumference to its diameter. This produces a number, and that number is always the same. However, the number is rather strange. The number starts as 3.141592653589793 and continues without end. Numbers like this are called irrational numbers.^[1][2][3]

The diameter is the largest chord which can be fitted inside a circle. It passes through the center of the circle. The distance around a circle is known as the circumference. Even though the diameter and circumference are different for different circles, the number ${\displaystyle \pi }$ remains constant: its value never changes. This is because the relationship between the circumference and diameter is always the same.^[4]

1. ↑ "Compendium of Mathematical Symbols". Math Vault. 2020-03-01. Retrieved 2020-08-10.
2. ↑ "Pi". www.mathisfun.com. Retrieved 2020-08-10.
3. ↑ Weisstein, Eric W. "Pi". mathworld.wolfram.com. Retrieved 2020-08-10.
4. ↑ Berggren, Lennart; Borwein, Jonathan M.; Borwein, Peter B. (2000). Pi, a Sourcebook. Springer Verlag. ISBN 978-0-387-98946-4.