What is a polyhedron?

A polyhedron is defined specifically as a three-dimensional shape that is formed by flat polygonal faces, which meet at edges and vertices. Each face of a polyhedron is a polygon, which means that all the sides of these faces are straight lines and they must completely enclose a space.

The characteristics of polyhedra include having a minimum of four faces (since a single polygon cannot enclose a volume by itself). Common examples of polyhedra include cubes, pyramids, and prisms. This definition distinguishes polyhedra from other 3-D shapes that may include curved surfaces or shapes that do not have properly defined faces, such as spheres or cylinders.

Understanding the concept of polyhedra is fundamental in geometry, as it lays the groundwork for exploring more complex 3-D shapes, their properties, and their applications in various fields, including architecture and engineering.