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What trig. identity is used here?

  1. Apr 9, 2010 #1
    4/t [cos(wt/2)-1] = -8/t sin(wt/4)

    ?
     
  2. jcsd
  3. Apr 9, 2010 #2

    nicksauce

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  4. Apr 9, 2010 #3
    double-angle formula, [itex]\cos(2\theta) = 1-2 \sin^2(\theta)[/itex] so [itex]\cos(2\theta)-1 = -2 \sin^2(\theta)[/itex] ... so your original formula is correct except for a missing square.
     
  5. Apr 9, 2010 #4
    Thanks a lot. :)
     
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