Young, George, jr, Baxter, Hubert Eugene, joint author · New York, Macmillan · leaf 89
l Relations of Point, Line, and Plane.A point can be represented by its projections only (§ 7). A linemay be represented by its projections, or by its traces (§§ 14,15, and 31). A plane can be represented satisfactorily only byits traces (§ 56). These facts should be clearly recognized,since many… … Fro. 69 Fio. 70 on normal-case planes, the projections of the points do not fallon the traces of the planes. Moreover, there is no simple re-lation between the projections of any point and the traces ofthe plane which contains it, beyond the fact that a (Fig. 70)must lie within the angle X XA, and…
Geometry, Descriptive
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