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Math Help - Trapezoidal Rule Problem

  1. #1
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    Trapezoidal Rule Problem

    \int_{0}^{1}13\cos(x)^{2} dx

    n = 4

    values of intervals

    are y_{0} = 13

     y_{1} = 12.9997525

     y_{2} = 12.99901002

     y_{3} = 12.99777261

     y_{4} = 12.996040


    change in x = \dfrac{b - a}{n} = \dfrac{1 - 0}{4} = 1/4

    By the trapezoidal rule

    \dfrac{change-in-x}{2}(y_{0} + 2(y_{1}) + 2(y_{2}) +2(y_3}) + y_{4})

    I got 12.998638 (rounded to 6 decimal places but this is wrong.
    Last edited by Jason76; August 3rd 2014 at 07:53 PM.
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  2. #2
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    Re: Trapezoidal Rule Problem

    Well, you can technically pull the 13 out to do the approximation first, and multiply it back in later on.
    But the thing is, is it cos(x^2) or cos^2(x)?
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  3. #3
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    Re: Trapezoidal Rule Problem

    Actually I realized what the problem is now: you are supposed to use radians, not degrees.
    Always switch your mode to radians for calculus.
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  4. #4
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    Re: Trapezoidal Rule Problem

    You have your calculator in "degree mode" when you should be using radians.
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