rewrite sin^(4) x so that it involves only the first power of cosine

1 Answer

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embizze | High School Teacher | (Level 2) Educator Emeritus

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`sin^4x=sin^2x*sin^2x`

`=(1-cos^2x)(1-cos^2x)`

`=(1+cosx)(1-cosx)(1+cosx)(1-cosx)`

`=(1+cosx)^2(1-cosx)^2`

Either of the last two equivalent expressions will work, as they both only involve cos to the first power.