can someone Plz help me understand PI?
pi is the ratio of the circumference of a circle to its diameter.
Given the diameter d, circumference = pi * d
or, given the radius r, circumference = 2pi * r
the area is pi r^2
pi is just a number, like 3 or square root of 2, or any other. It just happens to be given a name because it arises so frequently, especially in geometric contexts.