# Avondale Geo 3D

## 38 terms · unit 4

### polyhedron

a solid figure bounded by plane polygons or faces

### face

a flat surface of a polyhedron

### edge

the line segment along which two faces of a polyhedron intersect

### vertex

the point of intersection of lines or the point opposite the base of a figure

### regular polyhedron

any one of five solids whose faces are congruent regular polygons and whose polyhedral angles are all congruent

### convex

A polygon in which all vertices appear to be pushed outward.

### cross section

a section created by a plane cutting a solid perpendicular to its longest axis

### Platonic solids

tetrahedron, cube, regular octahedron, regular dodecahedron, regular icosahedron

### tetrahedron

any polyhedron having four plane faces

### octahedron

any polyhedron having eight plane faces

### dodecahedron

any polyhedron having twelve plane faces

### icosahedron

any polyhedron having twenty plane faces

### prism

a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms

### bases

The parallel sides of a trapezoid

### lateral faces

the faces that are not the base of a parallelogram

### right prism

each lateral edge is perpendicular to both bases

### oblique prism

a prism with lateral edges that are not perpendicular to the bases

### surface area of a polyhedron

the sum of the areas of the faces of the polyhedron

### lateral area of a polyhedron

the sum of the areas of the lateral faces of a polyhedron.

### net

An arrangement of two-dimensional figures that can be folded to form a polyhedron

### cylinder

a solid bounded by a cylindrical surface and two parallel planes (the bases)

### right cylinder

a cylinder where the segment joining the centers of the bases is an altitude

2πrh

2πrh+2πr²

### pyramid

a polyhedron having a polygonal base and triangular sides with a common vertex

### regular pyramid

a pyramid whose base is a regular polygon and whose lateral faces are congruent isosceles triangles

### circular cone

has a circular base and a vertex that is not in the same plane as the base

### lateral surface of a cone

LSA = ½PL
P is the perimeter/circumference of the base, L is the slant height

### right cone

A cone in which a perpendicular line drawn from the base to the tip (vertex) passes through the center of the base

### volume of a solid

1. Use a metric ruler
2. Measure the length, width, and height (Volume = l x w x h)
3. Units cubic centimeter (cm3)

### sphere

a three-dimensional closed surface such that every point on the surface is equidistant from the center

### center of a sphere

The point inside a sphere that is the same distance from every point on the sphere.

is a segment from the center to a point on the sphere

### chord of a sphere

a segment whose endpoints are on the sphere

### diameter of a sphere

a segment passing through the center, with endpoints on the sphere

### great circle

a circular line on the surface of a sphere formed by intersecting it with a plane passing through the center

### hemisphere

either half of the cerebrum

### similar solids

solids with the same shape and all their corresponding dimensions are proportional