SOLUTION: coul you help me about this?!? Prove the identity {{{Cos^2(2y)-4Sin^2(y)Cos^2(y)=Cos(4y)}}}

Algebra ->  Algebra  -> Trigonometry-basics -> SOLUTION: coul you help me about this?!? Prove the identity {{{Cos^2(2y)-4Sin^2(y)Cos^2(y)=Cos(4y)}}}      Log On

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