The Doctrines of Triangles: A History of Modern Trigonometry by Glen Van Brummelen

The Doctrine of Triangles is the second half of Glen Van Brummelen’s history of trigonometry. The first part, The Mathematics of the Heavens and the Earth [Van Brummelen 2009] dealt with the early history of trigonometry, from “precursors” in ancient Egyptian and Babylonian sources (dating from the second millennium BC), through to the trigonometric tables of Georg Rheticus in the 16th century AD. The present volume begins with a brief account of the story so far and then continues the story through to the early 20th century. It will be helpful to review briefly that “story so far”.