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Homework Help: Tough Problem

  1. Mar 6, 2007 #1
    Solve for all values of x:

    (cos2x)/(sin3x-sinx) = 1

    I found this problem and am having an extremely tough time solving it. I gotten down to a quadratic equation a couple of times, but it wouldn't factor. I am really stumped and really need some help. Thanks in advance.
  2. jcsd
  3. Mar 6, 2007 #2
    Don't you know how to solve all quadratic equations?
  4. Mar 6, 2007 #3
    Yes, I know how to solve quadratic equations, but I would get a negative under the radical and it would be undefined so the equation would not be possible. I think I found an answer and would like if someone could confirm this.

    For the final equation I got:

    sinx = 1/2

    and then I got:

    x = (pi)/6 + 2(pi)k
    x = 5(pi)/6 + 2(pi)k

    (Sorry, I don't know how to make a pi symbol)
  5. Mar 7, 2007 #4


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    Science Advisor

    You have shown really none of your work so it's impossible to say where you might have gone wrong. Reducing the orginal formula to sin x, I get a cubic equation which has an obvious root of sin x= 1/2 and the remaining quadratic is just 2x2- 1= 0!
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