Trigonometric function

In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. They are commonly defined as ratios of two sides of a right triangle containing the angle, and can equivalently be defined as the lengths of various line segments from a unit circle. More modern definitions express them as infinite series or as solutions of certain differential equations, allowing their extension to positive and negative values and even to complex numbers. All of these approaches will be presented below.

External links

• Dave's Short Trig Course uses interactive java applets that are very helpful for learning about trig functions on the unit circle, as well as being useful more generally for students of trigonometry.
• Javascript function grapher uses a javascript library to display functions. Works in nearly every modern browser.
• Cos Formula Program which allows you to find out a third side if you have the other two sides and an angle. Look under Cos Formula heading.