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Find all possiblie values of \(\cos(\theta)\) if \( \cos(2\theta) = 2\cos(\theta) .\)

 Oct 23, 2021
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I am pretty sure I saw this question answered yesterday.  Go see if you can find it.

 

Hint:

cos(2x)=cos^2x-sin^2x

and

sin^2x=1-cos^2x

 

simplify then sub   y=cos(theta)

then solve as a quadratic

 Oct 24, 2021

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