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Sinusoids homework help

  1. Sep 30, 2007 #1
    1. The problem statement, all variables and given/known data

    Express 8.5sin(290t+325) as C1cos(wt)+C2sin(wt)

    2. Relevant equations

    The previous parts of the problem actually ask to find the wave equation itself and write it in different forms. So the above wave equation can also be expressed as 8.5cos(290t-125) or as -8.5cos(290t+55) etc.

    3. The attempt at a solution

    Can I use the following trig identity: A cos (wt) + B sin (wt) = (A^2 + B^2)^1/2 cos (wt + tan^-1 (-B/A)) ?
  2. jcsd
  3. Sep 30, 2007 #2


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    It's easier than that. Use sin(a+b)=sin(a)*cos(b)+cos(a)*sin(b).
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