Elements of analytical geometry and the differential and integral calculus (1856)
Robinson, Horatio N. (Horatio Nelson), 1806-1867 · Cincinnati : J. Ernst · leaf 73
ER IV.The Parabola. Definition.—1. A parabola is a plane curve, every point ofwhich is equally distant from a fixed point and a given straightline. 2. The given point is called the focm, and the given line iscalled the directrix. To describe a parabola. Let CD be the given line, and F a gi-ven… … THE PARABOLA. 65 Put the other side of the square against the given line, CDyand with a pencil, P, in the thread, bring the thread up to theside of the square. Slide one side of the square along the lineCDy and at the same time keep the thread close against theother side, permitting the thread to…
Geometry, Analytic · Calculus
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