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OpenStudy (anonymous):
How do i prove the addition formula for cosine? Cos(u+v) = cos u cos v - sin u sin v
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OpenStudy (anonymous):
look in the book, i am sure it is proved there. if you know fancier math (say euler's formula) then this is a direct result of the laws of exponents. if not you have to use a geometric argument, and it is rather cumbersome although completely doable
OpenStudy (anonymous):
Unfortunately it doesn't prove it there. Do u know anywhere on a website where it proves it ?
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