An introduction to projective geometry and its applications; an analytic and synthetic treatment (1905)
Emch, Arnold, b. 1871 · New York, J. Wiley & sons; London, Chapman & Hall, limited · leaf 121
e, then its corresponding one is infinitelydistant. Hence / and the point at infinity on the horizontal io8 PROJECTIVE GEOMETRY. axis may be interchanged without disturbing the projectivity;the foregoing point-ranges form therefore an involution (§ 3).The double-points of this involution are the… … M Fig. 41. pole of the corresponding ray in T. Hence / contains the poleof /, and / and / form consequently a rectangular pair of thepolar involution around F. The polar involution of any pointon an axis contains, however, another rectangular pair, namely,the axis itself and the perpendicular to it…
Geometry, Projective · Geometry, Analytic
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