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Medially Similar (Posted on 2005-08-19) Difficulty: 2 of 5
Let ABC be a triangle, with M the midpoint of BC, and DEF a triangle, with N the midpoint of EF. Suppose that angle BAM equals angle EDN and angle CAM equals angle FDN. Show that triangles ABC and DEF are similar.

  Submitted by McWorter    
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Without loss we may assume that |AM|=|DN| and superimpose triangle DEF onto triangle ABC so that M and N coincide, E is on AB, and F is on AC. Since |BM|=|MC| and |EN|=|NF|, triangles BEM (equal BEN) and CFM (equal CFN) are congruent. Hence angles EBM and MCF are equal, whence BE and CF are parallel. This is a contradiction unless B and E coincide, and so also C and F coincide. Hence triangles ABC and DEF are similar.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re: A different wayMcWorter2005-08-19 22:43:01
SolutionA different wayOld Original Oskar!2005-08-19 17:39:53
SolutionSolutionBractals2005-08-19 15:11:03
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