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Article #808Re: Help with assignment problem, please!
From: Hrvoje Lakota
Date: Wed, 22 Mar 1995 01:19
Date: Wed, 22 Mar 1995 01:19
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In article <3kn6fh$1560@bubba.ucc.okstate.edu>, David Ullrich <ullrich@math.okstate.edu> wrote: >molinari@math.lsa.umich.edu (Rory Molinari) wrote: >> >> >>>>> "James" == James Xidos <jamesx@morgan.ucs.mun.ca> writes: >> In article <3kkpsv$m60@coranto.ucs.mun.ca> jamesx@morgan.ucs.mun.ca (James Xidos) writes: >> >> [snip] >> >> >>>> <tealsl@fox.nstn.ca> writes: >> >>>> >> >>>> > " A line goes through the point (2,2). It cuts the x axes at A >> >>>> > and the y axes at B. What is the minimum length of AB" >> >>>> >> >> [snipped: discussion of why answer is zero] >> >> In this problem we can get _any_ non-negative length for AB, so >> zero (although possibly trivial) is not an isolated answer, and >> we're not going to get anything non-zero by minimizing. > > Having made an ass of myself once already by overlooking the >trivial solution I feel uniquely qualified to say "Oh yeah? What line >gives you length(AB)=1?" > The minimum is zero but it's isolated - the next-largest >possibility is 4*sqrt(2). >Dave Ullrich. > How about this line: y=b/a*(x-a) where b = 1-sqrt(5)+sqrt(-7+4*sqrt(5))/2 = approx .5791517665 a = 2*b/(2-b) = approx .8152197436 This line passes through points (-a,0) and (0,b),the distance between which is 1, and it also passes through the point (2,2). As far as I can see this satisfies all the conditions of the original problem. Hrvoje Lakota
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109d8a,d5c0c74da6af7422 X-Google-Attributes: gid109d8a,public X-Google-Thread: 11ec76,d5c0c74da6af7422 X-Google-Attributes: gid11ec76,public X-Google-Thread: f86a3,d5c0c74da6af7422 X-Google-Attributes: gidf86a3,public X-Google-Thread: f7972,d5c0c74da6af7422 X-Google-Attributes: gidf7972,public X-Google-ArrivalTime: 1995-03-21 22:42:34 PST Newsgroups: can.schoolnet.math.sr,k12.ed.math,sci.math,mun.math.general Path: arc1-ca.pugleaf.net!nntp.gmd.de!dearn!blekul11!news.ysu.edu!usenet.ins.cwru.edu!gw1.att.com! fnnews.fnal.gov!mp.cs.niu.edu!vixen.cso.uiuc.edu!howland.reston.ans.net!math.ohio-state.edu!jussieu.fr!univ-lyon1.fr!swidir.switch.ch!epflnews!undergrad.math.uwaterloo.ca!hlakota From: hlakota@undergrad.math.uwaterloo.ca (Hrvoje Lakota) Subject: Re: Help with assignment problem, please! Message-ID: <D5tIBs.D4H@undergrad.math.uwaterloo.ca> Sender: news@undergrad.math.uwaterloo.ca (news spool owner) Nntp-Posting-Host: noether.math.uwaterloo.ca Organization: University of Waterloo References: <72576.tealsl@fox.nstn.ca> <eTD72c2w165w@ps2.xs4all.nl> <MOLINARI.95Mar20170301@bailey.math.lsa.umich.edu> <3kn6fh$1560@bubba.ucc.okstate.edu> Date: Wed, 22 Mar 1995 01:19:04 GMT Lines: 44