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.

CHAPTER IX
REPRESENTATION OF SURFACES WITH PLANE FACES
229. Surfaces consisting of Plane Eaces. Such surfaces are
usually placed, for ease of representation, in such a position that

b,
a,

Q,

d,

b' d'e'

a

U,

I'

FIG' 90
FIG. 90

FIG. 89

their principal faces are either perpendicular to or parallel to the
planes of projection.
Fig. 89 represents a cube in the third quadrant with two of
its faces parallel to H and with two of its faces parallel to V.

be,

g, ki
f, IC

a

a
f

g'. '
FIG. 91

1'

FIG. 92

Fig. 90 represents a cube, two of whose faces are parallel to H
but whose vertical faces are oblique to V.
89