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Math Help - Graphing Trig Functions (can someone check these)

  1. #1
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    Graphing Trig Functions (can someone check these)

    Okay so I have two problems i would like someone to check for me, i have to determine the amplitude, period, and phase shift of each function. Then i have to graph one period of the function. I don't know how to post my version of a graph here, but these are my calculations for the two equation i want checked so far.


    Equation : y = sin (x - PI / 2)


    Amplitude: 1

    Period: 2 PI

    Phase Shift : PI/2


    Step: PI/2

    X1: PI

    X2: 3PI/2

    X3: 5PI/2

    X4: 7PI / 2


    -----------------------------------------


    Equation: y = sin (2x - PI / 2)


    Amplitude: 1

    Period: PI

    Phase Shift: PI / 4

    Step: PI / 4

    x-values:

    X1: PI / 4

    X2: 3PI/4

    X3: PI

    X4: 5PI / 4
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  2. #2
    Super Member TheChaz's Avatar
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    Quote Originally Posted by MajorJohnson View Post
    Okay so I have two problems i would like someone to check for me, i have to determine the amplitude, period, and phase shift of each function. Then i have to graph one period of the function. I don't know how to post my version of a graph here, but these are my calculations for the two equation i want checked so far.


    Equation : y = sin (x - PI / 2)


    Amplitude: 1

    Period: 2 PI

    Phase Shift : PI/2


    Step: PI/2

    X1: PI

    X2: 3PI/2

    X3: 5PI/2 (This should be 2pi. Your increment is pi/2, which when added to your previous point 3pi/2, gives 4pi/2 = 2pi)

    X4: 7PI / 2 (Likewise, this is incorrect)


    -----------------------------------------...
    Notice the above edits.
    Actually, I prefer to use FIVE points (where we include the endpoints of the period). In this case, we would "start" at
    X0 = pi/2. Then
    X1 = pi
    X2 = 3pi/2
    X3 = 2pi
    X4 = 5pi/2

    Then we look at sine and (after adjusting/scaling by... 1 in this case...) our points are
    (X0, 0) = (pi/2, 0)
    (X1, 1) = ...
    (X2, 0)
    (X3, -1)
    (X4, 0)
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  3. #3
    MHF Contributor
    skeeter's Avatar
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    free graphing program ... Graph

    check your work yourself as you solve.
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  4. #4
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    ^ Thanks for the software. This is what i needed.

    Quote Originally Posted by TheChaz View Post
    Notice the above edits.
    Actually, I prefer to use FIVE points (where we include the endpoints of the period). In this case, we would "start" at
    X0 = pi/2. Then
    X1 = pi
    X2 = 3pi/2
    X3 = 2pi
    X4 = 5pi/2


    When i had PI / 2 under Step, i meant that as X0.


    Then we look at sine and (after adjusting/scaling by... 1 in this case...) our points are
    (X0, 0) = (pi/2, 0)
    (X1, 1) = ...
    (X2, 0)(X3, -1)
    (X4, 0)
    I just now noticed theres a pattern with the y-values for the sine curv ( This probably holds true in all cases for sine graphs) e. There are probably similar ones with the Cos curve. This should help me on my exam tomorrow. Thanks.
    Last edited by MajorJohnson; March 8th 2011 at 05:28 AM.
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