## Solid Objects

The following solids are frequently seen and used.

### Properties of Solids

 Solids are three dimensional (3D) objects which have length, width and height. A solid has faces, edges and vertices. (If an edge is hidden from view a dotted line or dashes are used.) The cuboid shown has: 6 faces 8 vertices 12 edges A prism is a solid with the same cross section or shape for all of its length A pyramid has a base which can be any shape and the corners of the base taper to a point called the apex. base

### Platonic Solids

 A Platonic solid is a regular polyhedron. A regular polyhedron is a solid in which all of the faces are the same shape and all the edges are the same length. The Platoninc solids were named after the Greek philosopher, Plato. There are only 5 Platonic solids. These are shown in the diagram on the right. The Platonic Solids Shape tetrahedron 4 faces − each a triangle cube 6 faces − each a square octahedron 8 faces − each a triangle dodecahedron 12 faces − each a pentagon icosahedron 20 faces − each a triangle