Primarily circles and spheres.
Pi (3.141...) is used for circles, and circles only. You use it to find the area and circumfrence.
You should know pi because of math. You need pi when you are dealing with circles. The only thing you really need to know about pi is 3.14 though.
Pi is a number that is never ending, but most people only use the first couple of digits. pi = 3.14159265 pi is the ratio of a circles' diameter to its circumference
Divide by pi and then divide by 2
Because all circles are similar.
In circles in nature.
circumference = 2*pi*radius or pi*diameter
Pi is very important for finding circumfrences and area's of circles.
Formulas relating to circles
To calculate properties of circles
Yes