# Happy Tau Day!

Every time I saw a Pi () symbol in mathematics that represented the value 3.141592653…, there was usually a “2” in front of it. This is no coincidence: a circle is the set of points that are the same distance from a center point, where is the radius, so the *radius* is what defines a circle—not the *diameter*. ^{1}

Now, the value of represents **the ratio of a circle’s circumference to its diameter**… wat? No wonder there’s always a persistent factor of 2 in almost every equation involving : The proper circle constant should be the ratio of a circle’s circumference to its

*radius*, or (see the figure below). This has a profound connection with radians and the trigonometric functions sine, cosine, tangent, etc. Even the Euler Formula looks better: .

This is not just me being non-conformist^{2}, this is actually part of a world-wide movement to correct the circle constant to what it should have been.