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Homework Help: Problem in trigonometric

  1. Apr 18, 2013 #1
    i got sinx/siny=1.2

    and i need to find cosx/cosy

    can i do it or maybe i need more knowledge?
     
  2. jcsd
  3. Apr 18, 2013 #2

    Simon Bridge

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    More information would help.
    Context perhaps?
     
  4. Apr 18, 2013 #3
    its a problem at optics and i need to solve this problem.
    that all i know from the problem given.
     
  5. Apr 18, 2013 #4

    Simon Bridge

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    It looks like you are trying to get an answer using an inefficient method.
    What is the problem you are doing?
     
  6. Apr 18, 2013 #5

    HallsofIvy

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    For example, if sin(x) and sin(y) are both positive, cos(x) and cos(y) could be positive or negative. So for one value of sin(x)/sin(y) there are two different possible values for cos(x)/cos(y).
     
  7. Apr 18, 2013 #6
    Why would it matter, u can say that sinx worth 0.5 and that's mean that cosx is positive and negative too.i just need a trigonometric connection between the two
     
  8. Apr 18, 2013 #7

    Simon Bridge

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    The general trig relationship between them is sin2θ + cos2θ = 1 because sinx and cosx are the opposite and adjacent sides of a right-angle triangle with unit hypotenuse.

    if sinx=1/√2, then cosx=1/√2
    But your problem is that you don't know what sinx is, what you know is the ratio of the sines of two angles ... sinx/siny.

    In general: if sinx/siny=S, for a known S, then sinx and siny can take on any values that satisfy sinx=S.siny ... infinite possibilities. You need to know something about the relationship between x and y to narrow them down.

    That is why I have asked for more information about the actual problem you are trying to solve.
    Without that information, nobody can help you.
    I do not understand your reluctance to share.
     
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