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Trig help

  1. Jan 10, 2007 #1
    I have the problem:

    0 = 3[cos(35)*cos(A) - sin(35)*sin(A)] - cos(A)
    where A is alpha...my unknown degree.

    somehow that turns into this:

    tan(A) = [cos(35) - 1/3] / sin(35)

    I am not drawing the connection or seeing how that is happening....

    Could you help???? THANKS
  2. jcsd
  3. Jan 10, 2007 #2
    Looking at the form we want, the first thing to do is divide by cos(A). Then at that point it is possible to seperate tan(A) from the other terms.
  4. Jan 10, 2007 #3
    Rearrange to give

    [tex] cos(35).cos(A) - \frac{cos(A)}{3} = sin(35)sin(A)[/tex]

    [tex]cos(A)(cos(35) - \frac{1}{3}) = sin(35).sin(A)[/tex]

    divide both sides by [tex]cos(A)[/tex] to give

    [tex](cos(35) - \frac{1}{3}) = sin(35).tan(A)[/tex]

    divide both sides by [tex]sin(35)[/tex] to give

    [tex]\frac{(cos(35) - \frac{1}{3})}{sin(35)} = tan(A)[/tex]
    Last edited: Jan 10, 2007
  5. Jan 10, 2007 #4
    oops, that y should be A

    EDIT: ignore that
    Last edited: Jan 10, 2007
  6. Jan 10, 2007 #5
    Thank you soooo much!
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