Date: 06/06/2001 at 11:20:41 From: Adam Peri Subject: Parabola Hi! I was wondering about the meaning of the word parabola. I think it's not Greek. Thanks, Adam
Date: 06/06/2001 at 16:14:53 From: Doctor Rick Subject: Re: Parabola Hi, Adam. Decent dictionaries include the etymology (origin) of words. Mine (Random House Webster's College Dictionary) says: [1570-80; < NL < Gk parabole an application. See PARABLE] In other words: the first known use of the word in English was in the 1570s. It is a New Latin word derived from the Greek word "parabole," meaning "an application." The etymology under "parable" adds that the Greek word also means "comparison" (relevant to the meaning of "parable"), and that it comes from the Greek prefix para-, "beside, alongside, of, by, beyond," plus the root bole, "a throwing." I must admit that the connection between "an application" and what we mean by parabola is not very clear. At the bottom of the first page of our Dr. Math FAQ http://mathforum.org/dr.math/faq/ you will find a link to the Web site "Earliest Known Uses of Some of the Words of Mathematics" by Jeff Miller. There we find information about the Greek origins of the word: PARABOLA was probably coined by Apollonius, who, according to Pappus, had terms for all three conic sections. Michael N. Fried says there are two known occasions where Archimedes used the terms "parabola" and "ellipse," but that "these are, most likely, later interpolations rather than Archimedes' own terminology." This still doesn't tell us why the word was chosen. We can make some guesses, though. If you track down the etymologies of the other conic sections, you'll find that "ellipse" is from a Greek word meaning "falling short" while "hyperbola" is from a word meaning "excess." If you consider the conic sections in terms of how they are obtained by slicing a cone, you see that the plane that produces an ellipse is less tilted than the side of the cone ("falling short"?); the plane that produces a hyperbola is more tilted than the side of the cone ("excess"?); and the plane that produces a parabola is parallel to the side of the cone. Thus, perhaps the idea is that a parabola "runs alongside" the side of the cone. That's only my best guess. Many math terms don't have a lot of meaning in themselves, that is, in their original meaning; mathematicians have put a very specific meaning into otherwise rather bland terms. - Doctor Rick, The Math Forum http://mathforum.org/dr.math/
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