It is once again Pi Day (March 14 or 3/14 in USA date format). I would just like to point out that the fractional representation of 22/7 is better than the three digits 3.14 thus the date of July 22 could be Pi Day also. If you want many more fun Pi Day posts, here are a few. Yes, Pi is indeed awesome.
Where Pi (π) is of course the number and r is the radius of the circle. Where does this formula come from? One method of obtaining this equation is to integrate dxdy over the area of a circle. Well, you probably wouldn’t want to do that in cartesian coordinates – but you get the idea.