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Okay, I don't even know where to start on this question. Hints (not full solution would be helpful :D )

 

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

 Oct 22, 2021
 #1
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$\cos \theta = \frac{3}{4}$

 Oct 22, 2021
 #2
avatar+2266 
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cos(2x) = 2cos^2(x) - 1

cos(2x) = 2cos(x)

2cos^2(x) - 1 = 2cos(x)

Any idea on what to do from here?

 

=^._.^=

 Oct 23, 2021
 #3
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quadratic in terms of cos(x)?

textot  Oct 23, 2021
 #4
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You got it   wink

 

Thanks catmg

Melody  Oct 23, 2021

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