1. Beauty, Form and Function: An Exploration of Symmetry
Asset No. 3
PART I
Concepts in Symmetry
Lecture I-2
Symmetry in Common Objects

2. Objectives By the end of this lecture, you will be able to:
define what ‘symmetrical’ means
recognize ‘asymmetrical’ objects
identify the basic features of point symmetry and one-dimensional symmetry
describe the beauty, form and function of point symmetry and one-dimensional symmetry

3. Symmetry in Common Objects
Symmetry is harmony of form based on a proportionate arrangement of parts.
Concise Collins Dictionary
Asymmetry is the lack or absence of symmetry.
Concise Collins Dictionary
Symmetric Objects
Asymmetric Objects
Observing symmetry
depends how you
look at something!

4. Automotive Symmetry How many mirror lines are in this alloy wheel? 6
Are all the mirror lines identical?
No, 2 unique
Point Symmetry is 6mm
Point symmetry exists when an object is built around a single point at the center of the figure. 
Number of
mirror lines?
360o/3
= 120o
Number of
mirror lines? 3
Identical mirror
lines?
No mirrors? What’s happening?
Yes
3-fold rotation
Point Symmetry is 3m
Point Symmetry is 3

5. Birds & Symmetry Repeating Units Mirror Asymmetric Unit Mirror Line
Roosting Birds
Standard
Representation
Mirror + Translation
Asymmetric Unit
Shore Birds
Glide Line

6. Summary Symmetrical objects contain matching parts within the whole.
Commonly recognized symmetry operations include reflection and rotation.
In point symmetry only reflection (mirror lines) and rotation (about a point occur).
In plane symmetry a compound operation called glide is introduced that a combination of reflection and translation.

7. Bibliographies Date Retrieved: 9 Jan 2014

8. Bibliographies Date Retrieved: 9 Jan 2014