Figure 6-25: Solids can't contain any extra edges or faces.  This gear is a solid. It's completely enclosed.  Not solid because of a missing face. (above)  Not solid because of a loose (extra) face. (above)  Not solid because of an extra interior face. (above)  Not solid because of loose edge on a face. (above)  Not solid because of a loose edge in midair. (above) |