
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.