Elements of descriptive geometry, with applications to isometric projection and othe forms of one-plane projection; a text-book for colleges and ingineering schools by O. E. Randall.

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DESCRIPTIVE GEOMETRY

32. Problem 8. Draw the two projections of a straight line situated
in the second quadrant parallel to H, oblique to V, and 2 units
from H.
33. Problem 9. Draw the two projections of a straight line situated
in the third quadrant perpendicular to H and 3 units from V.
34. Problem 10. Given a point M, 6 units back of V and 4 units
below H, also a point N, 4 units in front of V and 4 units above H;
required to draw the projections of the straight line located by the
points M and AV.
35. Problem 11. Draw the two projections of a straight line situated
in the fourth quadrant parallel to H and V and equidistant from H
and V.
36. Problem 12. Draw the two projections of a straight line situated
in the fourth quadrant perpendicular to V and 4 units from H.
FIG. 23 FIG. 24L
FIG. 23 FIG. 24
37. Representation of the Plane. The line in which a plane intersects H is called the horizontal trace of the plane. The line in
which a plane intersects V is called the vertical trace of the
plane.
If either trace of a plane intersects G-L, the other trace must
intersect G-L at the same point, otherwise G-L would intersect
the plane in two points.
If either trace of a plane is parallel to G-L, the other trace
must also be parallel to G-L, otherwise G-L would intersect the
plane while it was parallel to a straight line in the plane.
As a plane is completely determined either by two intersecting
straight lines or by two parallel straight lines, it is evident that a
plane is definitely located by its traces.