## Glossary: Module 5

All informal definitions are based on

my own experience and knowledge

### Term*: Reflection Symmetry*

* Informal Definition:*

One half of the picture looks exactly like the other half

*Formal Definition:*

A figure that contains a line along which a mirror can be

placed to reflect either half of the figure so it reproduces

the other half.

Definition from: Mathematics: A Human Endeavor, 3rd Edition

*Example of Reflection Symmetry:*

Example from: http://www.1stwebdesigner.com

**Term: Rotational Symmetry**

* ** Informal Definition :*

An object is moved around a middle point so it appears again

*Formal Definition:*

A figure that can be rotated through an angle of less than 360′

so that it coincides with its original position.

Definition from: Mathematics: A Human Endeavor, 3rd Edition

*Example of Rotational Symmetry:*

Example from: http://doyle.webnode.com

**Term: Regular Polyhedron**

* **Informal Definition:*

A solid that has same shape and size on each of its faces

*Formal Definition:*

A solid having faces in the shape of a regular polygon.

All of its faces, edges, and corners are identical.

Definition from: Mathematics: A Human Endeavor, 3rd Edition

*Examples of Regular Polyhedrons:*

Example from: http://www.math.rutgers.edu

### Term: Pyramid

* ** Informal Definition:*

Has a polygon base and triangle sides

*Formal Definition:*

A pyramid is a polyhedron with a polygonal base

and triangles for its faces.

Definition from: Icoachmath.com

*Example of a Pyramid:*

Example from: http://www.wiki.superdupergames.org

### Term: Prism

* ** Informal Definition:*

Has two same polygon bases and same size rectangle sides

*Formal Definition*:

* A solid with two congruent parallel faces, where any cross*

* section parallel to those faces is congruent to them.*

Definition from: http://www.mathopenref.com

*Example of a Prism:*

Example from: http://home.comcast.net

Jennifer,

The images really make all the difference to understanding. If you weren’t using this blog to create a glossary you could use your entries as part of a math word wall.

I look forward to seeing what you add next!

Pat