Young, George, jr, Baxter, Hubert Eugene, joint author · New York, The Macmillan Co. · leaf 199
of w, x, y, zare in the plane of the upper base, HA. The elements ofboth nappes can now be drawn on the V projection, as a^z, 182 DESCRIPTIVE GEOMETRY [VIII, § 159 If accurately determined, the V projections of the elementsshould all be tangent to the given V projection of the helicaldirectrix. Or… … Fig. 174 fd) to a developable helicoid. The lines ah, be, etc., are equal,and the angles abc, bed, etc., are equal. But the lines aj, jk,etc., are not equal, nor are the angles ajk, jkl, etc. If the surfaceis developed, the line a-i becomes a broken line, the componentparts of which are equal in…
Geometry, Descriptive
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