Sequence of polygons 
Quadrilateral bisection (II)
Instructions
Click on the blue dot and drag it to get several (green) quadrilaterals that give rise, by bisection, to the same (black) parallelogram. You can also change the obtained parallelogram by dragging its vertices (red points). Note that in this case we choose a parallelogram as the obtained quadrilateral and not an arbitrary quadrilateral. Why is that so?
