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anonymous
 one year ago
rewrite cos 3x with only sinx and cosx
anonymous
 one year ago
rewrite cos 3x with only sinx and cosx

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welshfella
 one year ago
Best ResponseYou've already chosen the best response.1Hint: cos 3x = cos (2x + x)

welshfella
 one year ago
Best ResponseYou've already chosen the best response.1use the identity cos (a + b) = cos a cos b  sin a sin b

welshfella
 one year ago
Best ResponseYou've already chosen the best response.1put a = 2x and b = x

welshfella
 one year ago
Best ResponseYou've already chosen the best response.1i'll start it off for you cos 3x = cos (2x + x) = cos 2x cos x  can you finish it off?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0\[\cos (A \pm B)=cosAcosB \mp\ sinAsinB\]
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