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Homework Help: Dihedral groups

  1. Feb 18, 2009 #1
    My goal is to prove that if n >= 3 then Dn, which is the dihedral group of size n is non-abelian.

    I am stuck, but my attempt at a solution was to show that some the symmetries in Dn are not commutative under composition, but I do not know how to prove that for n cases. My other attempt was to find a isomorphism to Dn and show that its isomorphism is not abelian, but I have no clue where to start from there.

    I would appreciate either an answer, or something to help me get going. Please be precise and I thank you so much in advance.
     
  2. jcsd
  3. Feb 18, 2009 #2

    Dick

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    In general, a rotation doesn't commute with a reflection.
     
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