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Homework Help: Sum of the e's

  1. Mar 24, 2007 #1
    1. The problem statement, all variables and given/known data
    I'm working on constructible things again and in one of the proofs our prof threw out this identity and I just don't know where it came from:
    HOW did he get that?

    Edit: I can't tell if the final term is supposed to be 2pi of 12 pi. I dunno.
    2. Relevant equations

    3. The attempt at a solution
    Last edited: Mar 24, 2007
  2. jcsd
  3. Mar 24, 2007 #2


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    Homework Helper

    Hint : geometric progression.

    The exponents on the Right Hand Side should be 2pi, not 12 pi.
  4. Mar 24, 2007 #3

    for n=natural number.
  5. Mar 24, 2007 #4
    Thanks. I see it now.
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