Perspective (geometry)

A diagram of perspective triangles

In geometry, two triangles are perspective (or homologic) if, when the sides of each triangle are extended, they meet at three collinear points. The line which goes through the three points is known as the perspectrix, perspective axis, homology axis, or axis of perspectivity. The triangles are said to be perspective from the line. The point at which the lines joining the vertices of the perspective triangle intersect is called the perspector, perspective center, homology center, pole, or center of perspectivity.

Karl von Staudt introduced the notation $ABC \doublebarwedge abc$ for the relation of triangles ABC and abc.

See also

• Desargues' theorem

References

• H. S. M. Coxeter (1942) Non-Euclidean Geometry, University of Toronto Press, reissued 1998 by Mathematical Association of America, ISBN 0-88385-522-4 .