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Homework Help: Summation of Trignometric Series

  1. Oct 31, 2007 #1
    Sum the following:

    Sin(x) + Sin(x+d) + Sin(x+2d)........+Sin(x+(n-1)d).

    I only know that summation of Sin and Cos functions whose arguments are in Arithmetic Progression can be done through telescopic series. But I dont know how to proceed. Please Help!
  2. jcsd
  3. Oct 31, 2007 #2
    Use the identity: Sin(x) = [Exp(ix) - Exp(-ix)]/(2i)

    Then you get two ordinary geometric series.
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