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Show two parrallelograms have same area

  1. Feb 7, 2012 #1
    This is a proposition from Euclid that I want to prove (see attachment). AD and EF lie on a line parallel to BC. I want to show that Area of ABCD = Area of BCFE. I believe to prove this I must first show that triangle ABE is congruent to triangle DCF (then show that triangle GBC = triangle GED).

    I know how to show that all the corresponding angles are the same for both triangles. I just do not know how to prove that the corresponding sides are congruent. Could you give me a clue on how to think about or begin showing that AB = DC or AE = EF or BE = CF? Thanks a bunch.
     

    Attached Files:

  2. jcsd
  3. Feb 7, 2012 #2

    tiny-tim

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    Hi DEMJR! :smile:
    But they're parallel lines cutting parallel lines (ie a parallelogram) …

    they're almost trivially equal :wink:
     
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