Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Identity for exponential function with imaginary arguments

  1. Jan 15, 2009 #1
    I have seen the following identity used.
    I can't find this in any book and I can't prove it myself.
    The left side equals 2isin(w/2)
    The right side equals cos(w)+isin(w)-1
    On the face of it, that seems to make the identity absurd
    How can one go about proving such an identity? Or is it wrong?
  2. jcsd
  3. Jan 15, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi ParityCheck ! Welcome to PF! :smile:

    (eiw/2 - e-iw/2)eiw/2 = eiw - 1 :wink:
  4. Jan 15, 2009 #3
    Thanks. I was making it way too complicated with trig identities and series and.....
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook