Pi Symbol

The Greek letter (pi) is used in trigonometry as a constant to represent a half-rotation around a circle in radians. The value of is approximately . The symbol appears in multiple geometric formulas.

Symbol Format Data
π Unicode


Pi | Concept

The greek letter π (pi) is a naturally occurring number that is defined by any circle's circumference divided by its diameter.

Circumference of Circle | Formula

The circumference of a circle is given the constant τ (tau) multpilied by the radius of the circle, where τ = 2π.

Area of Circle | Formula

The area of a circle is give by one-half multiplied by τ (tau) mutliplied by the radius of the circle squared.

Radians | Concept

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

Capital Pi | Symbol

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.