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Topic: Trapezoid definition
Replies: 26   Last Post: Oct 7, 2004 11:51 PM

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Lee Rudolph

Posts: 3,143
Registered: 12/3/04
Re: Trapezoid definition
Posted: Aug 9, 2000 2:19 PM
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Mary Krimmel asks:

>Now: it seems undisputable that the concept of counting numbers precedes
>the concepts of rationals, integers, and so on both in individual
>development and in social/mathematical history, but what about the
>geometric figures?
>
>I think that a circle comes first (and I see it not as a disk although
>that's what's usually presented to toddlers being prematurely tutored in
>"shapes") both for an individual and society? Then what?


This is a fascinating question. I hope someone has authoritative
information on it; I certainly don't! Anecdotally, I can mention
that I've been in quite a few caves in Spain (Tito Bustillo, Altamira,
...) and France (Lascaux--well, the replica thereof--,...), with wall
decorations from the Paleolithic era, and I've kept my eye out (and
occasionally asked guides) for evidence of the beginings of mathematics.
Groups of dots seem to be it, in that era, and those very rarely
(and ambiguously); no circles, arcs, disks, no straight lines or
broken lines or polygons. At least, I don't remember noting them;
I'd like to be corrected.

Jump forward to the Neolithic, though, as for instance in Valcamonica,
Italy, http://www.globalnet.it/graffiti/en_home.htm , and we find
engravings (not in caves! on huge, glacier-scrubbed flat rocks
outside, where they were lost to sight until about 20 years ago)
of spirals (circa 5500 years Before Present), see
http://www.geocities.com/Tokyo/2384/neol.gif ...
in another 1000 years, triangles (not abstract; images of
weapons) appear there, http://www.geocities.com/Tokyo/2384/2pini.gif .
But I suppose they're everywhere by then.

Lee Rudolph





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