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Homework Help: Trig Problem

  1. Apr 15, 2007 #1
    The question is Solve the trig equation for all values of the variable in the first positive rotation.

    Problem cos^2 3x = 1

    Heres how I attempted to solve the equation

    3x = arccos (1)^2

    1/3 arccos 1

    cos = 0 & 180

    However, on the test, the professor stated there were 4 more solutions & I'm having trouble trying to figure them out. What more do I need to do?
  2. jcsd
  3. Apr 15, 2007 #2


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    Homework Helper

    This is wrong.

    cos2(3x) = 1
    <=> cos 3x = +- 1
    Can you do the rest?
  4. Apr 15, 2007 #3
    Yes, thank you. I see what I did now & this helps.
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