OFTEN HAVING TRIANGULAR BASES, USED FOR DISPERSING LIGHT INTO A SPECTRUM OR FOR REFLECTING RAYS OF LIGHT.

a system or structure resembling a pyramid, as in hierarchical form.

a solid whose surface is generated by a line passing through a fixed point and a fixed plane curve not containing the point, consisting of two equal sections joined at a vertex.

a surface or solid bounded by two parallel planes and generated by a straight line moving parallel to the given planes and tracing a curve bounded by the planes and lying in a plane perpendicular or oblique to the given planes.

a line or border at which a surface terminates.

A flat surface of a polyhedron.

ONE OF THE TWO PARALLEL CONGRUENT FACES OF A PRISM.

A VERTEX OF AN ANGLE IS THE COMMON ENDPOINT OF THE RAYS FORMING THE ANGLE.

THE CROSS SECTION OF A SOILD AND A PLANE.