Rectangles Circumscribing a Quadrangle,
Forum Geometricorum, 18 (2018) 161—184.
Abstract. In this article we study the circumscribed rectangles about a quadrangle and in particular their extrema with respect to the area. We show that there are two such extrema represented by two similar rectangles. In addition we study the four similarities interchanging these extremal rectangles and show the existence of two twin quadrangles with given extremal rectangles.