Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Tricky Trig Function Find the eqn Help

  1. Aug 31, 2005 #1
    Find the equation of a sine function that has a vertical displacement 2 units down, a horizontal phase shift pi/3 to the right, a period of pi/6, reflection in the y-axis and the amplitude of 3.

    my answer [tex] y=3\sin [-12(x+\frac {\pi} {3})] -2 [/tex]

    is this what you get?
  2. jcsd
  3. Aug 31, 2005 #2


    User Avatar
    Homework Helper

    A sine wave function can be expressed generally as:

    [tex] f(x)=A\sin (\frac{2\pi x}{T}+ \theta}) + C [/tex]

    where A is peak to peak amplitude, T is period (or 1/T = frequency f), theta is phase shift (horizontal), and C is the vertical displacement.

    P.S. Your original question. Having the function be both even (reflected about the y-axis), and also forcing a phase-shift generally doesn't make sense (given you want a continuous function). Having both conditions satisfied would be purely coincidental.

    Edit: I forgot to note, when your theta is positive, the phase shift wil be to the left. A negative theta will result in a shift to the right.
    Last edited: Aug 31, 2005
  4. Aug 31, 2005 #3
    I think it should be pi/36 instead of pi/3 although I could be wrong.
  5. Aug 31, 2005 #4
    Anyone else get the same answer as me?
  6. Sep 2, 2005 #5
    At first glance it looks OK. The only thing I found is that for a phase shift to the right, it would be x-pi/3 rather than x+pi/3.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook