MathDB
orthogonal projection of quad is parallelogram

Source: Polish MO second round 1954 p5

August 29, 2024
geometry3D geometryprojectionparallelogram

Problem Statement

Given points A A , B B , C C and D D that do not lie in the same plane. Draw a plane through the point A A such that the orthogonal projection of the quadrilateral ABCD ABCD on this plane is a parallelogram.