GEOMETRIC GEMS (V2‪)‬

Our physical world is embedded in a geometric environment. Plane geometry has many amazing wonders beyond those that are briefly touched on at school. The quadrilateral, one of the basic instruments in geometry, has a plethora of unexpected curiosities. The authors present these in an easily understood fashion, requiring nothing more than the very basics of school geometry to appreciate these curiosities and their justifications or proofs.

The book is intended to be widely appreciated by a general audience, and their love for geometry should be greatly enhanced through exploring these many unexpected relationships in geometry. Geometric Gems is also suitable for mathematics teachers, to enhance the education of their students with these highly motivating quadrilateral properties.

Contents:
About the AuthorsAcknowledgmentsIntroductionQuadrilateral CuriositiesProofs of Quadrilateral CuriositiesToolboxIndex
Readership: The book is intended for the general readership, mathematics teachers, and mathematicians interested in extending their appreciation for geometry.

Alfred S Posamentier is currently a Distinguished Lecturer at New York City College of Technology of the City University of New York. Previously, he was the Executive Director for Internationalization and Sponsored Programs at Long Island University, New York. This was preceded by a five-year period where he was Dean of the School of Education and tenured Professor of Mathematics Education at Mercy College, New York. He is now also Professor Emeritus of Mathematics Education at The City College of the City University of New York, and former Dean of the School of Education, where he was tenured for 40 years.Robert Geretschläger retired from teaching Mathematics and Geometry ('Gymnasium') in 2022 after 40 years. During his career, he primarily taught at BRG Kepler, Graz Austria. Robert is also a lecturer (Geometry for future teachers) at Karl-Franzens University, Austria, and has been the team Leader of Austrian Team at International Mathematical Olympiad (IMO) since 2007. He is President of two societies: the World Federation of National Mathematics Competitions (WFNMC) and the Austrian Mathematical Kangaroo organisation. He is also a board member of AKSF (Association Kangourou sans Frontières). Robert has published many books on Geometry of Origami, Mathematical Competitions, popular geometry (a complete list is available at ).