Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site faron.UUCP Path: utzoo!linus!faron!bs From: bs@faron.UUCP (Robert D. Silverman) Newsgroups: net.puzzle,net.math Subject: Re: Polar Bear Problem Sequel Message-ID: <376@faron.UUCP> Date: Mon, 4-Nov-85 08:33:00 EST Article-I.D.: faron.376 Posted: Mon Nov 4 08:33:00 1985 Date-Received: Tue, 5-Nov-85 21:16:40 EST References: <855@whuxlm.UUCP> <593@hou2c.UUCP> <373@faron.UUCP>, <374@faron.UUCP> <327@mcgill-vision.UUCP> Organization: The MITRE Coporation, Bedford, MA Lines: 30 Xref: linus net.puzzle:1061 net.math:2114 > [ selected lines ] > > > such that the radius of a great-circle running E-W is the same as that > > of another great-circle running E-W which is 1 mile south. The only place > > this happens is the great-circle 1/2 mile north of the equator. Moving > > 1 mile south places you on the great-circle 1/2 mile south of the equator > > Thus, of the entire set of great circles (cardinality C) only 1 satisfies > > At latitude 90-theta, an East-West great circle has radius 2 PI r sin(theta) > a great circle. This does not bring one back to the point where one started > Then walking 1 mile north places one back on the original great circle, only > > Correct me if I'm wrong, but isn't a great circle a circle with its > center at the center of the earth (yes, I know the earth isn't a sphere, > but this discussion is pretending it is)? Everyone here seems to be > using it to mean a circle of constant latitude. > -- > der Mouse > > {ihnp4,decvax,akgua,etc}!utcsri!mcgill-vision!mouse > philabs!micomvax!musocs!mcgill-vision!mouse > > Hacker: One responsible for destroying / > Wizard: One responsible for recovering it afterward Oops!!! Bad terminology. You are indeed correct. A great circle does in fact have the center of the sphere as it's center. I should have said 'circle of constant lattitude.' The math is right but the names were wrong. I typed my response to the problem too quickly :-) Bob Silverman (they call me Mr. 9)