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#1 2007-08-26 23:02:57

tony123
Member
Registered: 2007-08-03
Posts: 228

90°

ABCD a parallelogram and BCED a cyclic quadrilateral , AN stret line cut interior segment CD in M and stret line BC in N ,let ME=NE=CE
show that  the  m(angle) betwen AN  and  CE  = 90°

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#2 2007-08-27 06:44:28

John E. Franklin
Member
Registered: 2005-08-29
Posts: 3,588

Re: 90°

What's a stret line?  cut CD in half at M?
cut CD into M parts?
I read about four points on a circle make a polygon.
Also cyclic triangles have formulas that might help.


igloo myrtilles fourmis

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#3 2007-08-28 23:03:07

tony123
Member
Registered: 2007-08-03
Posts: 228

Re: 90°

Consider five points A, B, C, D and E such that ABCD is a
parallelogram and BCED is a cyclic quadrilateral. Let ℓ be a line passing
through A. Suppose that ℓ intersects the interior of the segment DC at F
and intersects line BC at G. Suppose also that EF = EG = EC. Prove
that ℓ is the bisector of angle DAB

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