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Calculating the period of a harmonic function

  1. Aug 20, 2011 #1
    For a example, x=16cos(10t+5π/3) ,S.I.

    How am i supposed to calculate the period?(in order to do the graph)

    Thanks in advance
  2. jcsd
  3. Aug 20, 2011 #2


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    Science Advisor

    You cos function repeats when 10t increased by [itex]2 \pi[/itex]. See if you can work it out based on that.
  4. Aug 20, 2011 #3
    If we have something like this: f(x) = cos(at)

    then T= 2π/a

    But i really want to know if on my first example 5π/3 is playing any role on this formula.

    I mean if x=16cos(10t + 5π/3)

    Is period still T = 2π/a = 2π/10 ?
  5. Aug 20, 2011 #4


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    Yes it is. The phase constant (5 Pi /3) does not change the frequency or period.
  6. Aug 20, 2011 #5
    Nice. Thanks very much.
  7. Sep 3, 2011 #6
    What if you have a harmonic function with both cos and sin?

    such as: x(t)=4sin(15t)-3cos(9t+1.1)

    can you find the period of this analytically? I have found this has a period of 2.1 by plotting it in MATLAB, but can't figure out how to calculate this analytically...
    Last edited: Sep 3, 2011
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