Veblen, Oswald, 1880-1960, Young, John Wesley, 1879-1932 · Boston, New York [etc.] Ginn and Company · leaf 91
em 11. If 0 is any point and co any plane, there exists oneand only one perspective collineation in space having 0, co for centerand plane of perspectivity respectively, tohich transforms any point A-(distinct from 0 and not on co) into any other point A (distinct from 0and not on co) collinear… … Fig. 81 determined by the given conditions. We may assume B not on coand distinct from 0 and A. Suppose first that B is not on the lineAO (fig. 31). Since BO is an invariant line, B is on BO; and ifthe line AB meets co in L, the line AB = AL is transformed intothe line AL. Hence B is determined as…
Geometry, Projective
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