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how to solve for the integral of cos(2x) to the power of 4?

Hey again, so to write it out, it is as:

S cos(2x)^4 dx the 'S' is my integral sign.

anyone?

1 Answer

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  • 1 decade ago
    Favorite Answer

    Do it by first converting Cos(2x) into exponential form, it's easier. Integrate as follows:

    ∫ (Cos(2x))^4 dx =

    1/16 ∫ (e^2ix + e^-2ix)^4 dx =

    1/16 i(6x - e^4ix + e^-4ix - 1/8 e^8ix + 1/8e^-8ix) =

    3/8 x + 1/8 Sin(4x) + 1/64 Sin(8x)

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