Spanton, J. Humphrey (John Humphrey) · London, Macmillan and Co., Limited; New York, The Macmillan Company · leaf 192
is perpendicular to the side of the cone.Compare this figure with Fig. 228 (Plane Geometry).Let us now refer to Fig. 307. cfe is the inscribed sphere,/isthe point of contact with the cutting plane, ce is perpendicularto the side of the cone, and e determines the level of the planecontaining the… … SECTIONS OF SOLIDS. 179 meets the line DE in /: this is one of the foci of the elhpse,A hne drawn from d perpendicular to the cutting plane willdetermine the directrix ag. The line DE is the major axis of the ellipse, and if webisect this line by another at right angles to it, and obtain…
Geometrical drawing · Design · Drawing
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