# Avondale Geo 3D

## 38 terms

### Polyhedron

a solid figure bounded by plane polygons or faces

### Face

the front flat part of a 3d figure

### Edge

a sharp side formed by the intersection of two surfaces of an object

### 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

curving or bulging 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

optical device having a triangular shape and made of glass or quartz

### 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 its lateral faces

### Net

A two-dimensional pattern that can be folded to make a three-dimensional prism or pyramid

### 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

consists of all segments that connect the vertex with points on the base edge

### 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.

### Radius of a Sphere

a segment that has one endpoint at the center and the other endpoint 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

half of a sphere

### Similar Solids

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