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Wronskian help

  1. Feb 23, 2009 #1
    1. The problem statement, all variables and given/known data
    take the wronskian of [cos(theta)]^2 and 1+cos(2theta)

    2. Relevant equations

    3. The attempt at a solution
    so I set up the determinant

    [cos(theta)]^2 1+cos(2theta) as my y1 and y2 respectively and
    -2cos(theta)sin(theta) and -sin(2theta) as my y1 and y2 prime respectively

    i get my determinant to be -2cos(theta)sin(theta)*[cos(theta)]^2 +2cos(theta)sin(theta)*(1+cos(2theta)) the answer in the back says it should be 0. So I'm assuming I have to do something with basic trig identities to get it to 0? I can't seem to get it to go to 0 though I've been trying for 30 minutes :(. Can anyone offer some insight?
  2. jcsd
  3. Feb 23, 2009 #2


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    For one thing, I think your y2 prime should be -2sin(2 theta). (You briefly forgot the chain rule).
  4. Feb 23, 2009 #3
    ...wow I am an idiot! thanks I got it to simplify to 0 now haha sigh.
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