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Expressing sum of sines and cosines as a complex exponential

  1. Feb 9, 2014 #1
    If I'm given a function ##f(x) = A cos (x) + B sin (x)##, is there any way to turn this into an expression of the form ##F(x) = C e^{i(x + \phi)}##? I know how to use Euler's formula to turn this into ## \alpha e^{i(x + \phi)} + \beta e^{-i(x + \phi)}##, but is there a way to incorporate the second term into the first somehow, maybe with a change in the constants?
  2. jcsd
  3. Feb 9, 2014 #2


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    2017 Award

    Staff: Mentor

    You can use Euler's formula to express F(x) as sum of cos and sin and then find relations for the constants C and ϕ as function of A and B.
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