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Math Help - Find The Tangent Line Equation

  1. #1
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    Find The Tangent Line Equation

    I want to be sure I did this right
    I had to find the equation of the tangent line I was given

    f(x)=10-cos(3x) at x=\pi

    So I take the derivative with respect to x with meaning all I had to really do is take the derivative of the function so that gives me



    \frac{dy}{dx}=3sin(3x)

    which this gives me my slope when i plug in x
    which gives me 0

    and to find the y of the coords. I plug in x in the originial function and get 11

    and when i do point slope form i get

    y = 11 which cant be correct or is it?
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  2. #2
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    Quote Originally Posted by sk8erboyla2004 View Post
    I want to be sure I did this right
    I had to find the equation of the tangent line I was given

    f(x)=10-cos(3x) at x=\pi

    So I take the derivative with respect to x with meaning all I had to really do is take the derivative of the function so that gives me



    \frac{dy}{dx}=3sin(3x)

    which this gives me my slope when i plug in x
    which gives me 0

    and to find the y of the coords. I plug in x in the originial function and get 11

    and when i do point slope form i get

    y = 11 which cant be correct or is it?
    I followed the same method as you and got the same answer. Plotting the graph does rest on the line y=11
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  3. #3
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    Thanks mate, appreciated I dont want to continue on with something If I am doing it wrong
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