Wednesday, March 14, 2012

Happy Pi Day

I would have sworn I'd written about this holiday in the past, but I did not find it while searching.

March 14 (03/14) is Pi Day, in honor of the amazing number pi = 3.1459....

Pi is the ratio of a circle's circumference to its diameter, or in other words a circle is about 3 times around in length as it is across. But not exactly three and that little difference is very important.

In ancient Greece all the cool mathematicians did geometry and tried to accomplish everything with just a straight edge and compass. One goal that had them stumped was creating a square with the same area as a given circle. Since the area of a circle is pi * radius squared, a square with equal area would have sides of length = radius r  * square root (pi).  Today we know that pi and sqrt(pi) are impossible to construct manually.

For 2000 years after the Greeks, pi was only known to 10 decimals. The first major European contribution since Archimedes was made by the German mathematician Ludolph van Ceulen (1540–1610), who used a geometric method to give an estimate of π that is correct to 35 decimal digits. He was so proud of the calculation, which required the greater part of his life, that he had the digits engraved into his tombstone. (wikipedia)

In 1882 Ferdinand von Lindemann proved that pi is transcendental. This means its decimals never repeat, that it cannot be exactly expressed by any fraction and that it can never be created with a finite number of steps from integers or fractions. This is one reason we always refer to it by name or symbol because it can never be written down exactly using numbers like 3 or 3.1 or 3.1.4.

Bottom Line

Enjoy some pie on pi day!

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