
Altitude of a Cone
The segment with one endpoint at the vertex of a cone and the other in the plane that contains the base of the cone.

Altitude of a Pyramid
The segment with one endpoint at the vertex of a pyramid and the other at the center of the base of the pyramid.

Base of a Cone
The simple closed curve that bounds part of the cone.

Base of a Cylinder
One of two simple closed curves that lie in parallel planes.

Base of a Prism
One of two polygons that lie in parallel planes.

Base of a Pyramid
A polygon that bounds part of the pyramid.

Center of a Sphere
The fixed point in the interior of a sphere from which all points on the sphere are equidistant

Circular Cone
A cone whose base is a circle

Circular Cylinder
A cylinder whose base is a circle.

Concave Simple Closed Surface
A simple closed surface in which one or more segments* drawn between points on the surface lie partially or wholly outside the surface.

Concentric Spheres
Spheres that share a common center.

Cone
A surface that includes a simple closed curve and the segments that join all the points on that curve with a single fixed point not in the plane of the curve.

Convex Simple Closed Surface
A simple closed curve in which a segment joining any two points on the surface lies entirely in the interior of the surface.

Cube
A regular polyhedron with six faces, all of which are congruent squares.

Cylinder
A geometric surface composed of two congruent simple closed curves lying in parallel planes and segments of parallel lines joining the curves.

Dodecahedron
A twelvefaced regular polyhedron whose faces are all congruent regular pentagons.

Edge
The intersection of two polygons in a polyhedron.

Face
A polygon in a polyhedron.

Geometric Solid
A region in space bounded by a closed surface.

Hemisphere
Exactly half of a sphere.

Isocahedron
A twentyfaced regular polyhedron whose faces are all congruent triangles.

Lateral Edge
An edge of a polyhedron, usually refers to a prism or a pyramid.

Lateral Face of a Prism
The parallelograms of a prism whose edges are the segments that connect the bases.

Lateral Face of a Pyramid
The triangles of a pyramid.

Lateral Surface of a Cone
The set of segments that join the base of a cone with its vertex.

Lateral Surface of a Cylinder
The set of segments that join the bases of a cylinder.

Octahedron
An eightfaced regular polyhedron whose faces are all congruent triangles.

Polyhedron
A simple closed surface composed of regions of intersecting planesthese regions are polygons

Prism
A polyhedron composed of two congruent polygons that lie in parallel planes and the segments that are part of parallel lines that join the congruent polygons.

Pyramid
A polyhedron composed of a polygon and the segments that join that polygon with a fixed point not in the plane of the polygon.

Radius of a Sphere
A segment with one endpoint at the center of a sphere and the other endpoint on the sphere.

Regular Polyhedron
A polyhedron whose faces are congruent regular polygons

Regular Pyramid
A pyramid whose base is a regular polygon and whose altitude intersects the plane of its base at the center of the base.

Right Circular Cone
A circular cone whose altitude intersects with the plane of the base at the center of the base.

Right Circular Cylinder
A circular cylinder whose lateral edges are perpendicular to the planes that contain the bases.

Right Prism
A prism whose lateral edges are perpendicular to the planes of the bases.

Simple Closed Surface
A surface that divides space into three distinct regions: 1) points in the interior of the surface, which always form the endpoints of finite segments; 2) points on the surface; and 3) points in the exterior of the surface, which can form the endpoints of infinite segments.

Sphere
A surface whose points all lie an equal distance from a fixed point in space.

Surface
A geometric figure that traces the motion of a curve in space. A surface is twodimensional, but can span three dimensions.

Tetrahedron
A fourfaced regular polyhedron whose faces are all congruent triangles.

Vertex of a Cone
The fixed point that is the endpoint of all the segments that form the lateral surface of a cone.

Vertex of a Polyhedron
Any point on a polyhedron that is the intersection of three or more faces.

Vertex of a Pyramid
The fixed point at the intersection of all the faces of the pyramid.