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simple trigonometry problem

Discussion in 'Mathematics and Physics' started by bloody-orc, Apr 16, 2007.

  1. bloody-orc

    bloody-orc New Member

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    cos(2*x)+cos(4*x) = cos(x);

    How to solve this...
    It's too late and i just cant figure it out...
    i know x should = 1/2 Pi. but cant figure out how the hell to get that ;)
     
  2. Papabravo

    Papabravo Well-Known Member

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    Since the identity is not generally true, but only true for a particular value it reduces upon substitution to:

    +1 + (-1) = 0

    There is no general method that I know of for solving this kind of problem since it involves transcendental functions.
     
  3. bloody-orc

    bloody-orc New Member

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    Last edited: Apr 17, 2007
  4. dave

    Dave New Member

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  5. Papabravo

    Papabravo Well-Known Member

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    Truly, Estonians like Elbonians have dizzying intellects!
    ;)
     
  6. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,

    I know papabravo dosn't need me to back him up, BUT the solution to your
    problem did come from a States side web source!

    Give credit, where credit is due.

    Regards.
     
  7. bloody-orc

    bloody-orc New Member

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    the solutions were uploaded by me... ;):D freewebtown just gives me space to post my intelligence ;) And my remarks were not to offend anyone. especially Americans. You have much better university system than we do (yours just costs 450 000$ more). All they teach us is theory, but there it's all the other way around. more practical things and less "jibba-jabba"
     
  8. Papabravo

    Papabravo Well-Known Member

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    I was by no means offended, but I also don't feel stronly motivated to check your results. I'll be happy to stipulate that they are completely beyond my graduate level mathematics background. Like I said, you have a truly dizzying intellect. My head is still spinning. I am reminded of a particularly pedantic problem on my fresshman calculus exam.
    Code (text):

    Take the derivative of
     
    y = tan(x) ^ tan(x) ;
     
    In an engineering career spanning 40 years I've never found a use for that one.
     
    Last edited: Apr 17, 2007

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