Young, George, jr, Baxter, Hubert Eugene, joint author · New York, Macmillan · leaf 146
es.The group consists of the ellipse, the parabola, and the hyperbola(including the circle and straight line as special cases). If the conies are considered as being traced by a point movingin a plane, methods for their generation can be stated that donot involve the use of an actual plane cutting… … Eccentricity of the curve Fig. 123 Hne. The fixed point is called the focus, the fixed line thedirectrix, and the ratio is called the eccentricity. (See Fig. 123.) Variation in the shape of the different conies comes froma variation in the eccentricity. When the eccentricity is unity,the curve is…
Geometry, Descriptive
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