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From: gjk@talcott.UUCP (Greg Kuperberg)
Newsgroups: net.puzzle,net.jokes
Subject: Re: Re: Manhole covers (interview question)
Message-ID: <371@talcott.UUCP>
Date: Wed, 20-Mar-85 11:37:54 EST
Article-I.D.: talcott.371
Posted: Wed Mar 20 11:37:54 1985
Date-Received: Sat, 23-Mar-85 00:04:15 EST
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Organization: Harvard
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Xref: watmath net.puzzle:635 net.jokes:11471

>> Placed inside a square frame, one side of which is the length of the breadth
>> of the triangle, a Rouloux shaped drill bit can be made to follow the
>> edges of the square.
>> 				Mark Leeper
>
>Doesn't that produce a "square" with rounded corners?
>Doesn't the drill bit have to be exactly triangular to produce
>an exact square?
...
>   Norman Diamond

Nope.  Apparantly, the Rouloux drill bit has 90 degree corners.  This is
just the right angle for fitting in the corner of a square;  any other
angle (such as 60 degrees, as you suggest) would make the drill bit hit
the corner of the frame with a lot of force; the contraption would wear
down quickly.
---
			Greg Kuperberg
		     harvard!talcott!gjk

"No Marxist can deny that the interests of socialism are higher than the
interests of the right of nations to self-determination." -Lenin, 1918