# Two Models of Projective Geometry

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In the first model of 2D elliptic geometry, "points" and "lines" are the lines and planes through the origin in 3D, respectively. These axioms are satisfied: two "points" determine a "line" (because the two ordinary lines determine an ordinary plane), and two "lines" determine a "point" (intersect the two ordinary planes to get an ordinary line). There are no parallel "lines", because all ordinary planes intersect.

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Contributed by: George Beck (March 2011)

Open content licensed under CC BY-NC-SA

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"Two Models of Projective Geometry"

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Published: March 7 2011