March 29, 2017

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Cos(X+y)cos(x-y)= cos^2theta - sin^2theta

I foiled the left side as a start because I can kind of see sin^2+cos^2=1 but I can't finish.

  • Prove or Disprove - ,

    It can't be proved....unless you know what relationship Theta has with x and y.

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