390?-320? B.C.

Greek Mathematician

For many years, historians of mathematics cited Dinostratus as the first to achieve something approaching the squaring the circle—that is, finding a square equal in area to a given circle, using only a compass and straight edge. In fact it is impossible to do so, but Dinostratus came close by using a curve called a quadratix.

His life is a mystery, though Proclus (410?-485) maintained that Dinostratus was a close friend of Plato's (427?-347 B.C.) in Athens. Other than this, the only thing known about him was his use of the quadratix, a curve discovered by Hippias (fifth century B.C.).

In order to describe the quadratix, one must first imagine a square ABCD. Point A marks the center of a circle, the radius of which is labeled as AE. E is an arbitrary point of the curve BED, which forms...