Around 250 B.C., the Greek mathematician Archimedes calculated the ratio of a circle's circumference to its diameter. A precise determination of pi, as we know this ratio today, had long been of ...

Calvin T. Long, On the Radii of the Inscribed and Escribed Circles of Right Triangles-A Second Look, The Two-Year College Mathematics Journal, Vol. 14, No. 5 (Nov., 1983), pp. 382-389 ...