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How do I find the side length of a cross-section (as illustrated in the drawing below - cross-section in red) of a pyramid frustum/truncated pyramid?

alt text

I know the side-lengths of the top and bottom base, the height of the frustum and the distance to the cross-section. Furthermore I know the top and bottom base are parallel and that the center of the top and bottom base are directly on top of each other.

Glorfindel
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Tchami
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1 Answers1

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The proportions are linear, so just interpolate the lengths of the bottom and top sides with the proportion of the cut height with the total height.

cut_side = (cut_height/total_height)*(bottom_side-top_side)+top_side

(Anyway, double check it to be 100% sure).

fortran
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    alternatively: alpha*top_side + (1-alpha)*bottom_side, where alpha = cut height / total height – Jason S Aug 07 '09 at 13:40