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proving:
cos(4x) + cos(2x) = 2 - 2sin^2(2x) - 2sin^2(x)
Im not a kid asking you to do my homework. I did it a way, but I think that there would be a must simpler way.
I'm hoping to get some response, but this one could take awhile to figure out.
1 Answer
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- bskelkarLv 71 decade agoFavorite Answer
cos4x + cos2x
= 2 - [1-cos4x] - [1-cos2x]
= 2 - 2 (sin2x)^2 - 2(sinx)^2
Please checke the last term. It cannot be 2x there. It must be x
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