package coq-angles

The basis of the contribution is a formalization of the theory of oriented angles of non-zero vectors. Then, we prove some classical plane geometry theorems: the theorem which gives a necessary and sufficient condition so that four points are cocyclic, the one which shows that the reflected points with respect to the sides of a triangle orthocenter are on its circumscribed circle, the Simson's theorem and the Napoleon's theorem. The reader can refer to the associated research report (http://www-sop.inria.fr/lemme/FGRR.ps) and the README file of the contribution.