An elementary treatise on modern pure geometry (1893)
Lachlan, Robert · London, New York, Macmillan and Co. · leaf 170
of 0 in the point R. Then if thisline be turned about the point 0, so as to make the points Q andQ approach one another, the point R, which lies between them,will ultimately coincide with them. Hence, if P be the point ofcontact of one of the tangents from 0, when Q and Q coincide withthe point P,… … 154 POLAR PROPERTIES. be drawn. Let PP intersect QQ in S; and let PQ, PQ intersectin S. Then SS is the polar of 0. For 0, S, S are the centres of the tetrastigm PPQQ; andtherefore POQ meets SS in a point jR, which is the harmonicconjugate of 0 with respect to P and Q. Thus iJ is a point on the…
Geometry
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