advanced functions

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Prove that:
2sinxsiny = cos(x-y) - cos(x+y)

  • advanced functions -

    Rewrite the right side, using
    cos (x + y) = cos x cos y - sin x sin y
    cos (x - y) = cos x cos y + sin x sin y
    You should be familiar with those two identities.

  • advanced functions -

    kagr

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