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## Homework Statement

I need to find ∫cos^2 x using cos x cos y = 1/2(cos(x+y)+cos(x-y)). Note that it is not cos to the power of 2x. It is cos to the power of 2 multiplied by x.

## Homework Equations

cos x cos y = 1/2(cos(x+y)+cos(x-y))

## The Attempt at a Solution

I've searched my textbook and online everywhere, but my teacher hasn't given me any guidance. All I can think of is somehow converting cos x cos y = 1/2(cos(x+y)+cos(x-y)) to cos2x so I can then use a general formula/rule. Any help is highly appreciated.

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