## Introduction to trigonometry

Trigonometry comes from two Greek words:
trigōnon, "triangle" metron, "measure“ Trigonometry has been around since around the 3rd Century BC. Using basic trigonometry (SOHCAHTOA), you can calculate missing sides and angles in right-angled triangles. With more advanced work, you can use trigonometry in any triangle. It also has many applications in advanced mathematics. Click the picture or go direct to YouTube for a full explanation. |

## External Links

- Maths is Fun has a full set of written notes on the basics of trigonometry.
- GCSE.com also has a series of notes on trigonometry basics, with some problems to try.
- Check out IXL for online problems with full solutions - practise using the three trigonometric identities to calculate sines, cosines and tangents.