Plane and solid analytic geometry; an elementary textbook (1901)
Ashton, Charles H. (Charles Hamilton), 1866- · New York, C. Scribner's sons · leaf 131
the next article that the curve approaches coinci-dence with these lines. Such a line is called an asymptote.If we continue to increase 0, we see that there will beno real value of p until tan 6 again becomes numerically Vless than — Then p goes through the same changes in value, decreasing until… … Place the points F and D on the X-axis so thatF0=CF and Df C = CD, and draw DH perpendicular Ch. IX, § 66] CONIC SECTIONS 113 to the .X-axis. The symmetry of the curve again shows,as in the ellipse, that the hyperbola may be said to havetwo foci, .Fand F\ and two directrices, DJ3and B1W. We can now…
Geometry, Analytic
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![An illustration from L'optique divisée en trois livres : ou, l'On démontre d'une maniere aisée tout ce qui regarde 1. la propagation & les proprietez de la lumiere. 2. La vision. 3. La figure & la disposition des verres qui servent à la perfefectionner [sic] (1682)](https://img.insideoutlibrary.com/img/200/ia-loptiquedivise00ango-79-9.webp)
