Woods, Frederick S. (Frederick Shenstone), 1864-, Bailey, Frederick H. (Frederick Harold), 1865- · Boston, New York [etc.] Ginn and Company · leaf 91
nts is constant. The two fixed points are called the fori. Let them be denotedby F and F (fig. 72), and let the axis of x be taken throughthem, and the origin halfwaybetween them. Then if F isany point on the ellipse and2 a represents the constantsum of its distances from thefoci, we have FP+FP=2a.… … whence Let us now place 0A = a. OF OA = e> diere e<l. The quantity e is called the eccentricity of the ellipse.Then the points F and F are (± ae, 0). Computing the valuesof FP and FP by § 5 and substituting in (1), we have y/(x + aef+ y*+v(x — ae~)2+ y* (2) By transposing the second radical…
Geometry, Analytic · Calculus
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