Elements of analytical geometry and the differential and integral calculus (1856)
Robinson, Horatio N. (Horatio Nelson), 1806-1867 · Cincinnati : J. Ernst · leaf 76
tion, we shall have X : y : : y : 22>, a proportion showing that the parameter of the axis is a third pro-portional to any abscissa and its corresponding ordinate. PROPOSITION n. The squares of ordinates to the axis are to one another as their corresponding abscissas. Let X, y, be the… … THE PARABOLA. 67 PROPOSITIOJf III. The lotus-rectum is four times the distance from the focus tothe vertex. Let F VH be a parabola, F the focus, and Vthe principal vertex. FH, at right angles to DF,through the point F, is the latus-rectum. We are to prove that FB=^4FV. In the equation of the curve,…
Geometry, Analytic · Calculus
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