Pi Symbol
The Greek letter (pi) is used in trigonometry as a constant to represent a halfrotation around a circle in radians. The value of is approximately . The symbol appears in multiple geometric formulas.
Symbol  Format  Data 

π  Unicode 

TeX 


SVG 
Usage
The greek letter π (pi) is a naturally occurring number that is defined by any circle's circumference divided by its diameter.
The circumference of a circle is given the constant τ (tau) multpilied by the radius of the circle, where τ = 2π.
The area of a circle is give by onehalf multiplied by τ (tau) mutliplied by the radius of the circle squared.
Radians are a unit that measure angle using the radius of a circle. One radian is equal to the amount of rotation required to travel the length of one radius along the circumference of the circle.
Related Symbols
The capital Greek letter Pi (Π) is used in algebra to represent the product operator. The product operator has three parts: the initial index value, an end value, and the expression being multiplied together.