On a heightend plate, sand is poured until it overflows everywhere.
What shape of the sand heap is obtained ?

Video which shows you the formation of a sand heap:

On a 4 edges plate

In general, a roof shaped head is obtained with a ridge.
Under wich conditions is a pyramid-shaped heaps obtained ?

On a polygonal convex plate
For more than 6 edges, there are several possible shapes for the sand heap.
How to find all possible shapes ? On a convex plate, with 6 edges, 3 different shapes are obtained.

On a different shape of the plate
Connical egdes are found.
How to determinate if they are a parabola, an hyperbola or an ellipse ?

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