Parallelogram Dissection Paradox
This Demonstration shows a dissection paradox. On one hand, the area of the parallelogram is , and on the other hand, the area of the rectangle is . An explanation is in the Details section.
The red and blue diagonals and the green and brown diagonals are not parallel, so the figure is not a parallelogram. The slopes of the diagonals are and with a difference of , which is almost imperceptible.