The circle has fascinated mathematicians since ancient times. This entertaining book describes in layperson's terms the many intriguing properties of this fundamental shape. If math has intimidated you, this may be the ideal book to help you appreciate the discipline through one of its most important elements. The authors begin with a brief review of the basic properties of the circle and related figures. They then show the many ways in which the circle manifests itself in the field of geometry--leading to some amazing relationships and truly important geometric theorems. In addition, they explore remarkable circle constructions and demonstrate how all constructions in geometry that usually require an unmarked straightedge and a compass can also be done with the compass alone. Among other things, the reader will learn that circles can generate some unusual curves - many even quite artistic. Finally, the role of circles in art and architecture and a discussion of the circle's place on the sphere bring "full circle" this presentation of a key element of geometry.

Alfred S. Posamentier has published over fifty-five books in the area of mathematics and mathematics education, including, most recently, Numbers- Their Tales, Types, and Treasures (with Bernd Thaller). After having been on the faculty of the City College of the City University of New York for forty years, where he was a professor of mathematics education and dean of the School of Education, he subsequently held the same positions at Mercy College, New York, for five years.

Robert Geretschl ger is a mathematics teacher at Bundesrealgymnasium Keplerstrasse in Graz, Austria. He is also an adjunct member of the mathematics faculty at the Karl-Franzens University in Graz, the coach of the Austrian International Mathematical Olympiad team, and the president of the "Kangaroo" student mathematics contest in Austria. He is the author of Geometric Origami, among other works.