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Thread: Find the equation of the sine graph

  1. #1
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    Find the equation of the sine graph

    I need to find the equation of the sine graph below

    Find the equation of the sine graph-sineee.png

    I was able to find a, k, and c but how do I find d?

    So far I have f(x) = 5 sin (x - d) + 2

    I know I'm at the right track since the answer was given, y = 5 sin (x + π/3) + 2. What I want to know is how they got π/3, I think I can just plug in a point but I don't know how to solve it without ending up with a decimal answer.
    Last edited by khaezyline; Dec 13th 2017 at 08:57 PM.
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  2. #2
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    Re: Find the equation of the sine graph

    Starting at x= 0, going to the left, I see the graph crossing the x-axis half way between $-\pi$ and 0, at $-\pi/2$. And one full period is completed when it crosses the x-axis for the second time on the right, at a little larger than $2\pi/3$, perhaps at $3\pi/4$. It looks as if the period is $(3/4- (-1/2))\pi= 5\pi/4$. And the "phase shift" is from 0 to $-\pi/2$ so your "x- d" should be $x- (-\pi/2)= x+ \pi/2$.

    What is this "codecogs" that has contaminated this site?
    Last edited by HallsofIvy; Dec 14th 2017 at 04:36 AM.
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  3. #3
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    Re: Find the equation of the sine graph

    Thanks from khaezyline
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  4. #4
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    Re: Find the equation of the sine graph

    Quote Originally Posted by HallsofIvy View Post
    ... What is this "codecogs" that has contaminated this site?
    latex testing tags ...
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