At some point, we've learned about the existence of pi (more known as the Greek symbol π) as well as the different formulas it is used in for calculations related to circles. However, where did it actually come from, and how does it work? Keep reading to learn more!
Background
In Ancient Greek history, the mathematician Archimedes wanted to make an estimate to measure circles as it is difficult to have an exact measure for something that is not straight-edged. So, he came up with the number π.
As a known fact, π roughly equals to 3.14159..... but has an infinite number of decimals trailing afterward. "π" is a Greek symbol for the letter "p" which stands for the "perimeter" of a circle. It is a number present in many formulas used to make calculations with circular elements, such as:
Area of a Circle = π * r^2
Perimeter of a Circle = 2 * π * r
Volume of a Sphere = 4/3 * π * r^3
(r = radius of a circle)
How does it work?
How is π applicable to these formulas and able to be used to calculate them?
This part of understanding the value of π requires a little bit of imagination and abstract thinking: imagine the radius of the circle being bent.
That curved shape can be used to trace the circumference of the circle approximately three times before it covers the top half of the circle. (The exact value would be π--> 3.14159....)
So far, our equation is π * r because r is the measure of each curve. Due to the fact that different circles have different lengths of radii, the corresponding radius length of a specific circle will be plugged into the equation as r.
Since the circumference of the entire circle is the top AND the bottom, that number must be multiplied by 2, which is how we get:
Circumference = 2 * π * r
Thank you for reading and I hope this gave you a better understanding about the history of one of the most important symbols in mathematics!
FUN FACT!
To type "π" on a Mac, press "option + p" then release at the same time!
Written by: Janice Le
References:
Brown, Justin. “The Origins of Pi.”Primer, 31 Jan. 2012, www.primermagazine.com/2009/field-manual/know-it-all-the-origins-of-pi.
Also, shoutout to my math teacher during freshman year who actually gave me this lecture on pi's history! The diagrams are inspired by the way she had taught it :)
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