projection of any quarilateral can be a parallelogram (Chile 1994 P6)
Source:
May 27, 2019
geometryparallelogramquadrilateralprojection
Problem Statement
On a sheet of transparent paper, draw a quadrilateral with Chinese ink, which is illuminated with a lamp. Show that it is always possible to locate the sheet in such a way that the shadow projected on the desk is a parallelogram.