Ideal pointsThe properties of incidence in the euclidean plane show a lack of symmetry,
for while two distinct points always define a line, two distinct lines
either define a point or are parallel.
To achieve symmetry, we introduce additional points, called
ideal points for the plane.
A direction in E may be defined by a line through O, or as a class of parallel lines.
We must now define lines and incidence in Ê.
Incidence in Ê
|Geometry Page||Main Conics Page||Main Cabri Page|