# Pi Symbol (π)

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
960
TeX
\pi
SVG

## Usage

The greek letter π (pi) is a geometric constant approximately equal to 3.1456. The numeric value is equal to the length of any circle's circumference divided by its diameter.

The circumference of a circle is given the constant π (pi) multpilied by two times the radius of the circle.

The traditional formula for the area of a circle is given in terms of the geometric constant π (pi).

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.