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Math Help - Help with Trapezoidal Area

  1. #1
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    Help with Trapezoidal Area

    Find the trapezoid sum for .

    There's the problem I'm having, I keep trying to do it and I get really huge numbers and then get stuck. Can someone help get me started on it so I can see how you did it and if I'm not starting it off wrong I'll elaborate on what I keep doing.
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  2. #2
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    Quote Originally Posted by Eternal Calculus Student View Post
    Find the trapezoid sum for .

    There's the problem I'm having, I keep trying to do it and I get really huge numbers and then get stuck. Can someone help get me started on it so I can see how you did it and if I'm not starting it off wrong I'll elaborate on what I keep doing.
    It always helps to draw it out if you are in doubt.
    So sketch the function and draw the corresponding trapeziums.


    I assume by n = 2, you mean that you want 2 subdivisions.


    Since the horizontal distance is 2 units, then each subdivision will have horizontal distance of 1 unit.

    This is the same as the height of the trapezium.


    Now for the parallel sides of the trapezium, you will need to evaluate f(2), f(3) and f(4).

    Can you go from here?
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  3. #3
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    Given Formula

    The general summation formula for the trapezoid sum is:
    , where for all i


    This is the formula they give for working a trapezoidal sum, I understand how to read the problem its just every time I try to use their formula I get a different answer than any of the answers I'm left to choose from.
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  4. #4
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    Quote Originally Posted by Eternal Calculus Student View Post
    The general summation formula for the trapezoid sum is:
    , where for all i

    This is the formula they give for working a trapezoidal sum, I understand how to read the problem its just every time I try to use their formula I get a different answer than any of the answers I'm left to choose from.
    Read my response properly. I am giving you the "analytical version" of that formula.

    Try to work out all the dimensions of the trapeziums, work out their areas, then add them together.
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  5. #5
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    I realize what I was doing wrong, I was only halfing the first trapezium DX thank you for spelling it out for me! This really makes it a whole lot simpler for me haha
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