Descriptive geometry . n of a line withrespect to the coordinate planes by giving thequadrant in which it lies, together with its inclination with, and distance from, the coordi-nate planes. Line (7, Figs. 28 and 29, lies inthe first quadrant, and if read from a toward^, inclines upward, backward, and toward theright. The vertical projection indicates thatthe inclination is upward; the horizontal pro-jection indicates that the inclination is, at thesame time, backward; while either projectionindicates that the inclination is to the angle of inclination will be consideredlater. If the
Descriptive geometry . n of a line withrespect to the coordinate planes by giving thequadrant in which it lies, together with its inclination with, and distance from, the coordi-nate planes. Line (7, Figs. 28 and 29, lies inthe first quadrant, and if read from a toward^, inclines upward, backward, and toward theright. The vertical projection indicates thatthe inclination is upward; the horizontal pro-jection indicates that the inclination is, at thesame time, backward; while either projectionindicates that the inclination is to the angle of inclination will be consideredlater. If the line be read from h toward a, theinclination would be downward, forward, andto the left. Either is Fig. 30 illus-tiates four other lines as follows : Line ab^ in 5§, inclined upward, forward, and to the ed^ in 2Q^ inclined downward, back-ward, and to the ef^ in 4Q^ parallel to H^ inclined for-ward and to the gk^ in 5§, parallel to P, and inclinedupward and forward. LINES 11. Fig. 26 12 DESCRIPTIVE GEOMETRY 18. Planes. The position of planes may berepresented in projection as follows: 1. By the projections of two intersecting orparallel lines. 2. By the projections of a line and a point. 3. By the projections of three points not inthe same straight line. 4. By the lines of intersection with thecoordinate planes. (Traces.) All planes being indefinite in extent mustintersect one or both of the coordinate lines of intersection are called the tracesof the planes. Fig. 31 illustrates the inter-sections of the planes N with V and H, thevertical and horizontal traces being letteredFTVand ffiV, respectively. The orthographicrepresentation is shown in Fig. 32, save thatit is not always customary to continue thetraces beyond the ground line, the horizontaltrace being drawn on one side and the verticaltrace on the other, as in Fig. 40. Since the vertical trace of a plane is a linelying on FJ it may also be lettered as the verti-cal
Size: 2015px × 1240px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectgeometrydescriptive
