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Math Help - How do i find area of trapezoid using vector cross product?

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    How do i find area of trapezoid using vector cross product?

    i know the regular cross product gives the area of parallelogram, but how do i find the area of trapezoid?
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    Quote Originally Posted by MottoV2 View Post
    i know the regular cross product gives the area of parallelogram, but how do i find the area of trapezoid?
    You can partition any trapezoid into two triangles.
    The area of any triangle is one-half the corresponding parallelogram:
    \frac{{\left\| {\overrightarrow a  \times \overrightarrow b } \right\|}}<br />
{2}, where \overrightarrow a \;\& \,\overrightarrow b are adjacent sides.
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    so that means the area of trapezoid is same as the area of parallelogram?

    edit: oh wait, are they divided into identical triangles?

    edit again: k i got it :-D. thx
    Last edited by MottoV2; May 2nd 2009 at 11:15 AM.
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    They don't have to necessarily be equal.
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    Quote Originally Posted by MottoV2 View Post
    so that means the area of trapezoid is same as the area of parallelogram? edit: oh wait, are they divided into identical triangles?
    No. There are most likely two different triangles.
    Find the area of each and add together.
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