Trigonometry

The word trigonometry stems from the Greek words trigonon, which means triangle, and metrein, which means to measure. It began as a branch of geometry and was utilized extensively by early Greek mathematicians to determine unknown distances. The most notable examples are the use by Aristarchus (310-250 B.C.) to determine the distance to the Moon and Sun, and by Eratosthenes (c. 276-195 B.C.) to calculate the Earth's circumference. The general principles of trigonometry were formulated by the Greek astronomer, Hipparchus of Nicaea (162-127 B.C.), who is generally credited as the founder of trigonometry. His ideas were worked out by Ptolemy of Alexandria (A.D. c. 90-168), who used them to develop the influential Ptolemaic theory of astronomy. Much of the information we know about the work of Hipparchus and Ptolemy comes from Ptolemy's compendium, The Almagest, written around 150.

Trigonometry was initially considered a field of the science of astronomy. It was later established as a separate branch of mathematics—largely through the work of the mathematicians Johann Bernoulli (1667-1748) and Leonhard Euler (1707-1783).