||“Dynamic visual proofs” using DGS
||Irena ŠTRAUSOVÁ and Roman HAŠEK
Pictures and diagrams play an important role in the process of understanding various mathematical features. Moreover, an appropriate picture or diagram can be used as a visual proof of some geometric property or theorem. These non-verbal proofs, used to be called ‘proofs without words,’ are more attractive and acceptable to students than the classical proofs. The use of dynamic geometry or algebraic software removes the weak point of these proofs which lie in the fact that they mostly do not capture the chain of thought leading to the proof but only the result. The paper presents selected examples of such dynamic visual proofs created by dynamic geometry software in the form of materials that the authors use in the teaching of secondary school mathematics and in the mathematics teacher training programs. This paper also provides a comparison to their related classical proofs from contemporary textbooks.