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Homework Help: Proving identities

  1. Sep 11, 2008 #1
    1. The problem statement, all variables and given/known data
    prove: cos^2(x)= (1+cos2x)/(2)

    2. Relevant equations
    i broke the cos^2(x) down to 1-sin^2(x)???

    3. The attempt at a solution
  2. jcsd
  3. Sep 11, 2008 #2


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    Homework Helper

    It's easier to start with the right hand side. Just apply the double angle formula on the right.
  4. Sep 11, 2008 #3
    this is what i did:

    = (1+cos2x)/(2)
    = (1+ (2cos^2(x)-1))/(2)
    = 2cos^2 (x)/2

    look good?
  5. Sep 11, 2008 #4


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    Homework Helper

    Yeah looks ok.
  6. Sep 11, 2008 #5
    awsome thanksman
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