Prove the identity.cos 4x + cos 2x = 2 - 2 sin2 2x - 2 sin2 x

What will be an ideal response?


cos 4x + cos 2x = cos2 2x - sin2 2x + cos2 x - sin2 x = 
1 - sin2 2x - sin2 2x + 1 - sin2 x - sin2 x = 2 - 2 sin2 2x - 2 sin2 x.

Mathematics

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