Smart, Edward Howard · London : Macmillian and Co. · leaf 45
r. But suppose that the only available drawing implement atour disposal were a straight edge.^ The straight line would then be the primary element, thepoint being determined by two intersecting straight lines,and becoming thus the secondary element. *Miss C. A. Scott, Modern Idea>i and Methods… … Fig. (5. We have therefore a dual way in which geometrical figuresmay be obtained according as the generating element is apoint or a straight line. Let us consider a few of the simplest examples of suchfigures. We arrange them side by side, taking for the left-hand side the point as the primary…
Geometry, Projective
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