Projective geometry for use in colleges and schools (1911)
Milne, William P. (William Proctor), 1881- · London : Macmillan · leaf 73
ce the plane X is drawn containing the normalPP to it, .. X is perpendicular to it. Since QQ lies in X and is perpendicular to thecommon section I of X and it, .. QQ is perpendicularto it. Similarly we can shew that the locus of the feet ofall perpendiculars drawn from points on I on to ttis I.… … Fig. 29. THE CONIC 63 Let Il and L be tlieir orthogonal projections in theplane tt . Now the projection of the intersection of l^ and Z^ isthe intersection of l^ and Io. But Zj and U meet at infinity. Hence l^ and Z^ intersect at infinity,i.e. l[ and Z2 are parallel. 30. // ttvo lines be parallel,…
Geometry, Projective
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