Geometry Chapter 12

orthogonal drawing

the tw0-dimensional top, left, front, and right views of a three-dimensional object

corner view

the view from a corner of a three-dimensional figure

polyhedron

a three-dimensional figure bounded by polygons, called faces

face

flat side of a polyhedron

edges

line segments where the faces of a polyhedron meet

prism

a polyhedron with two congruent, parallel bases connected by parallelograms

bases

one of two faces of a polyhedron, which are congruent and parallel

regular prism

a right prism with bases that are regular polygons

pyramid

a three-dimensional figure with one base that is a polygon and triangular faces that meet at a point, called an apex

regular polyhedron

a polyhedron in which all faces are regular congruent polygons

cone

a three-dimensional figure formed by a circular base and a curved surface rising to a single point, called an apex

sphere

the set of all points in space equidistant from a given point, called the center

cross section

a two-dimensional shape formed in a plane by slicing that plane through a three-dimensional object

net

a two-dimensional figure that when folded forms the surfaces of a three-dimensional object

surface area

the sum of the areas of all faces and side surfaces of a three-dimensional figure

lateral faces

faces that are not bases

lateral edges

edges not part of the base

right prism

a prism with lateral edges that are also altitudes

oblique prism

a prism in which the lateral edges are not perpendicular to the bases

lateral area

for prisms, pyramids, cylinders, and cones, the area of the figure, not including the bases

right cylinder

a cylinder with an axis that is also an altitude

oblique cylinder

a cylinder that is not a right cylinder

axis (0f a cone)

segment with endpoints that are the vertex and the center of the base

regular pyramid

a right pyramid with a regular polygon as its base

slant height

the height of one of the faces of a pyramid or the length from a cone's base to the vertex, represented by a cursive l

right cone

a cone with an axis that is also an altitude

oblique cone

a cone that is not a right cone

great circle

for a given sphere, the intersection of the sphere and a plane that contains the center of the sphere

hemisphere

half of a sphere and the great circle that divides it

Platonic Solids

the five regular polyhedra: tetrahedron, hexahedron, octahedron, dodecahedron, or icosahedron

cylinder

a three-dimensional figure with two congruent, parallel circular bases

perspective view

the view of a three-dimensional figure from the corner

axis (of a cylinder)

segment with endpoints that are the centers of the bases