Smart, Edward Howard · London : Macmillian and Co. · leaf 185
^ Acad. Brussels,1822) ; and Pierce Morton (Trans. Camb. Phil. Soc, 1829).] THE FOCI 157 The sphere touches the cone along a circle MLM, whoseplane is perpendicular to the axis of the cone. Let the plane MLM cut the plane of the section in thestraight line XK. Take any point P on the section, and… … Fig. 81. Then MLM and NPQ being parallel planes, NP is parallel toXK. Also each of these lines is perpendicular to AA, foreither is the common section of two planes, each of which isperpendicular to the plane of the paper. Join VP. This line is a generator of the cone, and thereforepasses through…
Geometry, Projective
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