Young, George, jr, Baxter, Hubert Eugene, joint author · New York, The Macmillan Co. · leaf 150
roughk and h. 120. To approximatea Parabola by Arcs ofCircles. Establish anynumber of points thatare known to lie on theparabola (Fig. 129,points v, 1, 2, 3, etc.),by the method of§§ 115, II, or 116.Draw the normals atthese points (§ 119). The axis is a normal at the vertex.Prolong these normals to… … Note. . c> f =focus X2,y3 etc., II 0X15.2b II xf, 30 II yf i etc. Fig. 129 See footnotes to §§ 110 and 113. Also note that the principle hereused may be applied to the construction of an ellipse (§ 127, III) or ofan hyperbola. 134 DESCRIPTIVE GEOMETRY [VII, § 121 121. The Ellipse. An ellipse is…
Geometry, Descriptive
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