Smart, Edward Howard · London : Macmillian and Co. · leaf 252
have a common raj Q,QA. .•. they are in perspective, andtlu? intersections of QB, QjB ;QC, QiC ; QD, Q,D are collinear. But three points on a coniccannot be collinear (Chap. VIII.§2). .. no such points as Qj canexist. … Then, by supposition, Qi {abed } =p{abcd } = q\ abed}. But qi{abcd} and q{abcd} havea common point. .*. they are in perspective, andthe joins of qb, q^b; qc, q^c ; qd,q^d are concurrent. But three tangents to a coniccannot be concurrent (Chap. VIII.§2). .*. no such lines as q-^ can exist.
Geometry, Projective
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