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

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Philippe 92

Posts: 614
Registered: 1/25/05
Re: Geometry Problem
Posted: Feb 20, 2008 7:56 AM
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I.M. Soloveichik wrote :
> There is not enough information unless that angle at D which looks like it is
> 90 is supposed to be 90--in that case the angle x is 40 degrees.

A constructive proof that there is enough information to get the
*angles* :

Construct on a given base EB the 4 rays with given angles, they
intersect into C and D.
Starting from a different base EB gives just a simiular figure,
hence with all same angles.

And of course the "9O° looking" angle is ... not 90°, but 110°.


Philippe C., mail :
site : (recreational mathematics)

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