Smart, Edward Howard · London : Macmillian and Co. · leaf 284
a tangent g parallel to h may be found. Thecentre of the parallelogram formed by a, /, h, g is the centreof the conic. 256 PROJECTIVE GEOMETRY We can now construct the asymptotes of a fivctangentconic. For by the last article we can construct the tangentsfrom the centre just found, and these are… … Fig. 129. Let V, V, P, Q be the given points ; denote the rays VP, VQ,VP, VQ by a, b, a, b respectively, and draw a^, b^ through Vparallel to a, b. Now the cross-axis for two homographic pencils at vertex Vtouches the circle (of § 4, Chap. XVI.) when the conic is aparabola. Describing then this…
Geometry, Projective
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