Young, George, jr, Baxter, Hubert Eugene, joint author · New York, The Macmillan Co. · leaf 211
Fig. 179 194 DESCRIPTIVE GEOMETRY [VIII, § 171 171. To Draw a Line Tangent to a Double-Curved Surface ofRevolution at a Given Point on the Surface. If a plane cutsfrom the given surface any curve, any line in the cutting planeand tangent to the curve is tangent to the surface (Fig. 153). In Fig.… … Fig. 180 passed through x. -This plane will cut a parabola from thesurface. The projection of this parabola could be determinedby the method of § 149, and the tangent could be drawn atonce. It will be found easier, however, to rotate the entire con-struction (toward the right, in the figure) on the…
Geometry, Descriptive
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