Respuesta :

it is pi 3.14159265359
and you use it for a circle
irspow
π is a constant that arises when the circumference of a circle is divided by its diameter. mathematically:

π=C/d, where C=circumference of a circle and d=diameter of circle.

It is most commonly used to find the circumference, diameter, radius, and area of a circle.  But it also has many other uses such as a measure of angles in radians.