Smart, Edward Howard · London : Macmillian and Co. · leaf 250
respectively thepoint of intersection of their otherpair of common tangents and thetangent at their point of contact. CoR. 3. If we remove the re-striction that the ranges are notto be in perspective, the conic-envelope reduces to the point iwand the centre of perspective ofthe ranges. It is, in… … Fig. 1136. For, if possible, let two conies bedrawn through the five points A,B, C, D, E. Let any line through A cut theseconies in P and Q. Then, by §2 (a), A{PEDC[=B{PEDC}. For, if possible, let two conies bedrawn to touch the five lines a,h, c, d, e. Take any point on a and drawfrom it tangents…
Geometry, Projective
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