© HalfTauDay
March 14, or 3/14, is known as "Pi Day" because of its resemblance to the first three digits in the decimal expansion of π (pi), which is defined as the ratio of a circle's circumference to its diameter:
π= C/D = 3.14...
As "the circle constant", π is the object of virtually unlimited adulation, so you are
probably under the impression that π is a particularly important number. I am sorry
to report that you have been misinformed.
The true circle constant is the ratio of a circle's circumference to its radius, not to its diameter. This number, called τ (tau), is equal to
2π, so π is 1/2 τ - and March 14 is thus Half Tau Day. (Of course, June 28, or 6/28, is Tau Day itself.) Although it is of great historical importance, the mathematical significance of π is simply that it is one-half τ.
Take a look at the website here
Well. don't throw in the tau!
(I'm SO ashamed)
Somehow, a ? got added at the end of the URL.
Here's the correct link:
[Link]