# Trigonometry

## Historic Development Of 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).

## Additional topics

Science EncyclopediaScience & Philosophy: *Toxicology - Toxicology In Practice* to *Twins*Trigonometry - Historic Development Of Trigonometry, Angles, Triangles And Their Properties, Right Triangles And Trigonometric Functions