# Elementary Trigonometry

- By: Richard W. Beveridge
- Publisher: Clatsop Community College
- Source: [LibreTexts](https://math.libretexts.org/Bookshelves/Precalculus/Elementary_Trigonometry_(Beveridge))
- Licence: [CC BY-NC-SA 3.0](https://creativecommons.org/licenses/by-nc-sa/3.0/)
- Read at LibreTexts: https://math.libretexts.org/Bookshelves/Precalculus/Elementary_Trigonometry_(Beveridge)
- PDF: https://downloads.libretexts.org/api/v1/download/math-37205/pdf

Ancient trigonometry typically used angles and triangles that were embedded in circles so that many of the calculations used were based on the lengths of chords within a circle. The relationships between the lengths of the chords and other lines drawn within a circle and the measure of the corresponding central angle represent the foundation of trigonometry - the relationship between angles and distances.