Two triangular pyramids of same base and height are cut by a horizontal plane. The apexes D and E can be dragged horizontally and independently. [br]Drag G to change the height of the cutting plane. The cross sections should be the same. [br]View from top to see more clearly the shape of the bases and sections.[br]According to the Cavalieri's Principle*, the volume of these pyramids should be equal.

* [url]http://en.wikipedia.org/wiki/Cavalieri's_principle[/url]