- Steve Phelps
In Euclidean geometry, Varignon's theorem states the midpoints of the sides of an arbitrary quadrangle form a parallelogram. A common task for students is to determine the conditions which lead to a rhombus, rectangle, or square. Activate the ROTATE 3D GRAPHICS VIEW tool, and see that this theorem holds in three dimensions. Determine the conditions which lead to a rhombus, rectangle, and square.