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Figure 6.6 Figure 6.7

6.2 POINTS AND LINE ON THE SURFACE OF THE SOLID

The point lies on a surface if lies on a line lying on this surface (Fig. 6.8).
The line lies in a face if its two points lie in this face (Fig. 6.8).

Figure 6.8

Auxiliary intersection
It may be proved by geometry that if any prism, pyramid is cut by a plane parallel to the
base, the intersection is always a figure like the base in shape, and parallel to it in position (Fig.
6.9).

Figure 6.9

Auxiliary intersection is often used for face point finding.

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