Higbee, F. G · New York, John Wiley & Sons · leaf 32
on that these pointsand lines have to theplanes of projection mustbe known. In drafting a point isalmost never designatedby a letter, but in descrip-tive geometry it has beenfound convenient to indi-cate points and lines bythis means. A point inspace is indicated by thecapital letter, as A, B,… … Fig. 25. Thus: the plan view of the point A is a, and its elevation is a,and when the point A is referred to it means the actual pointin space. The line MN means a line in space whose plan viewis mn and whose elevation is mn. 22 ESSENTIALS OF DESCRIPTIVE GEOMETRY The relation that a point or a line…
Geometry, Descriptive
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