Activity 8: Johnson Solids
A Johnson solid is a strictly convex polyhedron, each face of which is a regular polygon, but which is not uniform.
There is no requirement that each face must be the same polygon, or that the same polygons join around each vertex.
As in any strictly convex solid, at least three faces meet at every vertex, and the total of their angles is less than 360 degrees. Since a regular polygon has angles at least 60 degrees, it follows that at most five faces meet at any vertex.
Although there is no obvious restriction that any given regular polygon cannot be a face of a Johnson solid, it turns out that the faces of Johnson solids always have 3, 4, 5, 6, 8, or 10 sides.
Use the pieces in the GeoGenius construction kit to make some of the Johnson Solids (or all 92!). Here are 5 examples for you:
L-R: 1.Triaugmented Dodecahedron 2. Gyroelongated Square Bicupola 3. Augmented Truncated Cube
4. Gyrate Bidiminished Rhombicosidodecahedron 5. Disphenocingulum
► Click here to download a pdf of Johnson Solids