3D Shapes

3D Shapes

1. Polyhedra (shapes with only flat faces)

   • Pyramids
     • Polygon base with triangle faces meeting at apex
       • Regular (regular base)
       • Irregular (irregular base
   • Prisms
     • polygon base with rectangle sides and congruent cross section all along its length
       • Regular (base is regular)
       • Irregular (base is irregular)
   • Platonic Solids (3d shape where each face is the same regular polygon, and the same number of polygons meet at each vertex, same angles)
     • Tetrahedron, hexahedron, octahedron, dodecahedron, icosahedron

2. Variations

   • Oblique (when edges or prism/cylinder don't form right angle with base, or apex of pyramid or cone isn't directly above the centre of the base
   • Truncated (when a section of the shape has been "cut off" and a new face is there instead of the usual vertice

3. Non polyhedra (shapes that have one or more curved faces)

   • Cone (circular base, 1 vertex)
   • Torus (made by revolving a circle about an axis in the same plane)
   • Sphere (every point same distance from centre, no vertex or edges)
     • Hemisphere (half a sphere, has one flat face)
     • Spheroid (irregular sphere - not all points same distance from centre)
   • Cylinder (2 identical flat circular ends and 1 curved side, with same cross section at all points)