It utilizes dynamic geometry software, specifically GeoGebra, to explore the statements and proofs of many of the most interesting theorems in the subject. Topics covered include triangle centers, ...

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°..

When calculating angles using a circle ... theorem applies. It may not be possible to calculate the missing angle immediately. It may be necessary to calculate another angle first. Tangents ...