2.C.a.R. is dynamic geometry program simulating compass and ruler constructions on a computer. But on a computer, much more is possible.
-Ruler and compass constructions can be changed by dragging one of the basic construction points. The student can check the correctness of the construction and gain new insights.
-Tracks of points and animated constructions can help to understand geometric relations. Tracks can be used as new objects to explore.
-With the macros of C.a.R. very complicated constructions become possible. Macros are also a way to organize the geometric thinking.
-Hiding construction details and using colors make constructions clearer to read. In C.a.R., lines and circles can also be reduced to the relevant points.
-Arithmetic computations, numerical solutions, curves and functions go beyond classical constructions. It is even possible to construct in 3D using advanced macros.
-Other geometries, hyperbolic or elliptic, can be explored.
C.a.R. works on all modern platforms. Constructions and assignments can be embedded into web pages easily. C.a.R. has been translated in many languages.
C.a.R. can be used free of charge, and the source is available under the GPL license.
http://zirkel.sourceforge.net/
