Smart, Edward Howard · London : Macmillian and Co. · leaf 279
t whose point of contact is at infinity. Every parabola touches the line at infinity. vSo that aparabola may be drawn to satisfy four conditions, i.e. to passthrough four points or touch four lines. The direction of the axis being given is equivalent to twosuch conditions ; for a tangent and its… … Fig. 127. Let A, B, C be the three given points and d, e the straightlines giving the directions of the asymptotes. Then two more 252 PROJECTIVE GEOMETRY points on the curve, D„ at infinity on d and E«, at infinity on e,are known. If F^^ be another point on the curve at infinity,either D„F^ or E^F^…
Geometry, Projective
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