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Determine the rms value for the given function

  1. Apr 23, 2013 #1
    1. The problem statement, all variables and given/known data

    Determine the rms value of v(t) = 15 + 10cos(20πt)


    2. Relevant equations

    Vrms = √(1/T*∫T0v2dt

    3. The attempt at a solution

    √(10*∫0.10[15+10cos(20πt)]2dt

    Unless, I'm much mistaken I should be able to plug the equation into the formula I have given above. I used the integral function on my calculator to do the calculation and I got 24.98V but the answer is supposed to be 16.58V

    Any suggestions for where I'm going wrong?
     
  2. jcsd
  3. Apr 23, 2013 #2

    TSny

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    Homework Helper
    Gold Member

    Your setup is correct. You must have made a mistake in the integration with your calculator.
     
  4. Aug 13, 2016 #3
    Vrms = √15^2+(10/√2)^2 = 16.58 V
     
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