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gjhfdfg

  • 3 years ago

Use an angle sum identity to verify the identity cos 2 (theta) = 2 cos^2 (theta) - 1

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  1. zepdrix
    • 3 years ago
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    Rewrite it like this. \[\cos(2\theta)=\cos(\theta + \theta)\] Then you need to remember your angle sum identity for cosine :) \[\cos(\alpha+\beta) = \cos \alpha \cos \beta - \sin \alpha \sin \beta\] See if you can figure it out from there! :)

  2. gjhfdfg
    • 3 years ago
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    So, 2+2? for a + b?

  3. zepdrix
    • 3 years ago
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    Theta + Theta for a and b :\

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