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Homework Help: Show that

  1. Dec 26, 2009 #1
    Show that cosh(2z)=cosh^2(z)+sinh^2(z)

    ???
     
  2. jcsd
  3. Dec 26, 2009 #2
  4. Dec 26, 2009 #3
  5. Dec 26, 2009 #4
    Hmm, I was just considering z as a random variable label, could just as easily be a, theta, or x.

    So comparing to cos(2z) == cos2z - sin2z, there is a product of 2 sines, which you flip the sign of when comparing to hyperbolics, so cosh(2z) == cosh2z + sinh2z
     
  6. Dec 26, 2009 #5

    tiny-tim

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    Welcome to PF!

    Hi Wardlaw! :smile:

    (try using the X2 tag just above the Reply box :wink:)
    You should get some e-2z also. :confused:

    Show us what you got for the RHS. :smile:
     
  7. Dec 26, 2009 #6
    Re: Welcome to PF!


    Oh yeah you are correct, my mistake. I can't even read my own working :)
    How exactly do you go about solving thi problem?
     
  8. Dec 26, 2009 #7

    tiny-tim

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    I leave it to you. :smile:
     
  9. Dec 26, 2009 #8
    Solved:biggrin:
     
  10. Dec 26, 2009 #9

    tiny-tim

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    :biggrin: Woohoo! :biggrin:
     
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