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Homework Help: Help solving a trig equation.

  1. Mar 17, 2009 #1
    1. The problem statement, all variables and given/known data
    Tan[60 degrees]=Sin[theta]/(1/3+Cos[theta])

    2. Relevant equations
    Trig identities?

    3. The attempt at a solution
    Tan[60 degrees]=Sin[theta]/(1/3+Cos[theta])
    (1/3+Cos[theta])Tan[60 degrees]=Sin[theta]
    1/3 Tan[60 degrees]=Sin[theta]-Tan[60 degrees]*Sin[theta]

    Now I'm lost...
    I can put it in mathematica, and get a solution of 1.34004 Radians or 76.7786 degrees. I just don't know how to solve it!
  2. jcsd
  3. Mar 17, 2009 #2

    Tom Mattson

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    Staff Emeritus
    Science Advisor
    Gold Member

    OK so far.

    The line is wrong. Your cosine morphed into a sine, so you'll need to fix that. I would actually back up to the previous line, leaving the cosine and sine on different sides. Look at [itex]\sin(\theta)[/itex] on the right side. Use a Pythagorean identity to express it in terms of [itex]\cos(\theta)[/itex].
  4. Mar 19, 2009 #3
    Thank you, I was able to get to the solution!
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