signals and systems

Discussion in 'Homework Help' started by saradahm, Aug 10, 2008.

  1. saradahm

    Thread Starter New Member

    Aug 10, 2008
    Huy guys....have the following questions from signals and systems....

    Determine whether the following signals is periodic...If it is periodic determine its fundamental period....

    a) 2cos(9t+pi/6)
    b) x(t) = sin^2(t-pi/6)
    c)x[n] = cos((pi*n^2)/8)
    d)x[n] = 5sin((3pi/8)*n) + 3cos((pi/6)*n)

    I have attached the file with the questions.....
  2. roddefig

    Active Member

    Apr 29, 2008
    See [post]78406[/post].
  3. silvrstring

    Active Member

    Mar 27, 2008
    That's nice. Where's your work?
  4. roddefig

    Active Member

    Apr 29, 2008
    What do you mean?

    Edit: Ack, sorry, I thought silvrstring was the OP. Disregard my question.
    Last edited: Aug 11, 2008
  5. blazedaces

    Active Member

    Jul 24, 2008
    roddefig gave you your answer. We're not here to do your homework for you.

    But just to add a comment, it might help for part d to know that the sum of two periodic signals is periodic if the ratio of their individual fundamental frequencies is a rational number.

    Think about the concept. Periodic. Plot each of those out using matlab or a calculator and look at the signals. Periodic means it repeats. Now think about that and think about the info roddefig gave you. You can easily connect the dots.

    Good luck,