**March 13. The day known to the nerd community as “Pi Day”! The day of “π”.**

Why that day? Because if you write that date in the American way (3/14) you get the first three digits of Pi! Pi day is almost as awesome as the Star Wars Day. The fact that Star Wars get its day at May 4th, just because “May the fourth be with you” is another level of “AWESOME”!

Another worth mentioning fact is that, if you see **Pi on a mirror, you get the word “Pie”** (Mind = Blown!)

Happy #PiDay. pic.twitter.com/XZHH5aDZTJ

— Google UK (@GoogleUK) March 14, 2016

The first large scale celebration of Pi Day was in 1988 at the San Francisco Exploratorium, where Larry Shaw organized a happening where he and his colleagues marched around a circular space and then consumed a lot of… Pies!

Assuming that since you are at this web page, you already know what π is, let’s talk about the Length of an Arc of a Circle.

Circular arc is a segment of a circle, or of its circumference (boundary) if the circle is considered to be a disc. Central angle is an angle whose apex (vertex) is the center of a circle and whose legs (sides) are radii intersecting the circle in two distinct points and thereby subtending an arc between those two points whose angle is (by definition) equal to that of the central angle itself. It is also known as the arc segment’s angular distance. Arc lengths are denoted by s, since arcs “subtend” an angle.

The length of an arc of a circle can be calculated multiplying the central angle (measure in degrees) with π and the radius of the circle, dividing by 180 degrees (the semi perimeter of the circle).

The equation is the one on the left, where **s** is the arc’s length (m), **π** is pi, **r** is the circle’s radius (m), **a** the angle that corresponds to the arc and **hc** is the Half circle!

Go ahead, check this equation and search whatever else you want to solve. You will find some help in our fxSolver video.

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