What up pi is:
Pi is the ratio of the circumference of a circle to its diameter. It has many uses including finding the Circumference, surface area, arc length and volume.
How pi finds the circumference:
The circumference of a circle is equal to 2*pi*r
When you substitute pi into this equation: C = 2 * pi * r,
you are using Pi to find the Circumference of a Circle. Pi is an irrational number that is used to determine the Circumference of a Circle.