Smart, Edward Howard · London : Macmillian and Co. · leaf 290
has a constant cross-ratio. .*. by § 7 (b), Chap. XIV., the envelope of k is a conic, i.e. C,the polar reciprocal of C, is a conic. § 4. Prop. Pole and polar with respect to C reciprocateinto polar and pole with respect to C, the reciprocal conic. … Fig. 130. (For the sake of clearness the base conic X is not shewn inthe figure.) Let O be any point in the plane of the conic C. Then to O corresponds as its reciprocal with respect to thebase conic a line o in the plane of the conic C. RECIPROCATION 263 To a line / through O corresponds a point L…
Geometry, Projective
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