A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles, is ...

The volume of a 3D shape is the amount of space inside it. Volume is measured in cubic units such as cm³ and m³. The volume, or capacity, of liquids is measured in millilitres or litres. The surface ...