3D Geometry

Looking at 3D geometry is interesting. Well, at least I think so since I can't draw for the life of me. In this post I'll break down geometry that comes in three dimensions.

Simple closed surface: has exactly one interior, no holes, and is hollow. An example of this would be a sphere. 

Polyhedron: a simple, closed surface made up of polygonal faces. An example of this would be a soccer ball. 

See how the ball is made up of a whole bunch of hexagons and pentagons?

Prism: a polyhedron in which two congruent faces (bases) lie in parallel planes and the other faces (lateral faces) are bounded by parallelograms. The name of the prism starts with the name of the bases.

For example:

Hexagonal Prism

Octagonal Prism

Triangular Prism

Not too bad so far, right? Stick with me!

Pyramids: Polyhedron determined by a polygon and a point not in the plane of the polygon. Just like the prism, the name of the pyramid is determined by the shape of the base. 

Regular polyhedra: a convex polyhedron whose faces are identical regular polygons.

Examples:

Cylinder: a simple, closed surface that is NOT a polyhedron. Has two simple closed curves called bases and a lateral surface.

Cone: the union of line segments connecting to a point.