Bailey, Frederick H. (Frederick Harold), 1865- · Boston, London, Ginn & Co. · leaf 167
aken perpendicular both to the base of the cone and to thecutting plane. This plane necessarily contains the axis of thecone, and hence passes through the centre of each circularsection of the cone. Let MN be the intersection of OAB andthe cutting plane. We have then to distinguish three cases.… … Fig. 68. The new sections are circles of which the lines FG and H Kare diameters. QP, the intersection of the planes FG andMN, is perpendicular to the plane OAB and hence perpen-dicular to the lines FG and MN by Solid Geometry. Forsimilar reasons, CR is perpendicular to HK and MN. Now, since the…
Geometry, Analytic
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