Where did Pi come from?
Date: Fri, 2 Dec 1994 10:20:16 EST From: 904 Subject: question Good day, Dr. Math: We are an adult high school and we were wondering if you could answer our question. Where did the word pi come from, and how did someone determine it was equal to 3.14? Thank you, Margie at TCLFLA5.
Date: Mon, 5 Dec 1994 15:09:11 -0500 (EST) From: Dr. Sydney Subject: Re: question Dear Margie: Thanks for writing Dr. Math! We are more than happy to answer your questions. Pi is defined to be the ratio of the circumference of a circle to the diameter of a circle. Say you have a circle of radius 1. Then the circumference of the circle is 2Pi(1) and the diameter is 2(1), so the ratio of the circumference to the diameter is Pi. Anyway, Pi is an infinite decimal that is approximately equal to 3.14. People have worked on approximating Pi for thousands of years. For instance, Archimedes approximated Pi by inscribing polygons in the circle and taking the ratio of the circumference of the polygon to the radius of the circle (which is also the "radius" of the polygon). The more sides on the polygon, the more accurate the approximation. So, if you inscribe a dodecagon (12-sided polygon) and compute the ratio of the circumference to the radius, you will get a better approximation than if you do the same for a hexagon (6 sides). This makes sense if you draw it out. The polygons with the greater number of sides more closely resemble circles. It is important to remember Pi does not equal 3.14; instead, 3.14 is an approximation for Pi. Really Pi = 3.141592653... (it is an infinite decimal). Mathematicians began notating this ratio with the Greek letter Pi around 1706. Perhaps the letter Pi was chosen to represent "periphery" (Pi is the ratio of the circumference (periphery) to the diameter). I hope this helps. If not or if you have any other questions, please feel free to write back. Thanks! --Sydney, Dr. "Math Rocks"
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