Descartes’ theorem, a cornerstone of geometry, defines the relationship between four mutually tangent circles. But for centuries, generalizing the equation to more than four circles had eluded ...

Graphs of Sine and Cosine 1.2 An applet illustrating how the graphs of sine and cosine are related to the unit circle ... of the Tangent to a Parabola 2.1 An applet illustrating how the tangent to a ...

A tangent is a straight line which touches the circle at a point but does not cut through the circle. There are two theorems involving tangents. The angle between a tangent and a radius is 90°..