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Mathematics 15 Online
OpenStudy (anonymous):

Verify the identity. cos 4x + cos 2x = 2 - 2 sin^2 2x - 2 sin^2 x

OpenStudy (anonymous):

I would start on the left hand side. Use the double angle formula for cos(2x), in the form cos(2x)=1-2sin^2(x). For the cos(4x), write it as cos(2*(2x)) and you will be able to use the double angle formula twice. That should get you started (:

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