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Topic: Geometry Problem
Replies: 17   Last Post: Feb 20, 2008 10:04 AM

 Messages: [ Previous | Next ]
 Carl Barron Posts: 152 Registered: 12/13/04
Re: Geometry Problem
Posted: Feb 18, 2008 11:55 PM

In article <MPG.22243347aced4a5d9899a1@news.cc.tut.fi>, Kaba
<none@here.com> wrote:

> > Hi all,
> >
> > I need help with this problem:
> >
> > http://img180.imageshack.us/img180/8286/20080218181526nq7.gif
> >
> > The angle to find is ECD.
> >
> > The matter is solving it without trigonometric functions.
> > With trigonometry or by drawing it you can see that the angle to find
> > is 20° (sessagesimal) but I can't find it using a simple solution
> > (properties of triangles, the parallel postulate and so on).
> >
> > Can you solve it?

>
> Interesting problem, couldn't solve it either. I get 4 unknowns but only
> 3 linearly independent equations.

consider triangles BDC and ECD and their angles as well as
intersecting and straight lines. Pretty easy no real equations
just bookkeeping....

Date Subject Author
2/18/08 rb
2/18/08 mensanator
2/18/08 none@here.com
2/18/08 rb
2/19/08 Philippe 92
2/19/08 rb
2/20/08 Carl Barron
2/20/08 Philippe 92
2/20/08 rb
2/20/08 Philippe 92
2/20/08 rb
2/18/08 Carl Barron
2/19/08 Nat Silver
2/19/08 rb
2/19/08 I.M. Soloveichik
2/19/08 rb
2/19/08 briggs@encompasserve.org
2/20/08 Philippe 92