The Real Projective Plane

The specification real simply means that we are considering a projective plane whose coordinates, if we were to calculate them, would all be real numbers. So now, what is the projective plane? Projective geometry is based on the Euclidean geometry that we all know and love, but it is more generalized. The projective plane can be thought of as a Euclidean plane with the addition of a line at infinity. The addition of the line at infinity closes the projective plane, giving it special properties that the Euclidean plane does not share.

A page about the projective plane with helpful diagrams.

The Geometry Center's page about the real projective plane.

Source:"The Real Projective Plane" by H. S. M. Coxeter (Cambridge University Press, 1960)

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