1. Symmetry What is reflectional symmetry? What is rotational symmetry?
What is point symmetry?
What is glide reflection symmetry?

2. Types of Transformations
The types of transformations that we have already studied are:
Translation
Rotation
Reflection
Dilation
Slide
Turn
Mirror image
Bigger/smaller

3. Reflectional Symmetry
Reflectional symmetry, (line symmetry, mirror symmetry, bilateral symmetry)—a figure has reflectional symmetry if it can be reflected across a line in such a way that the resulting image coincides with the original figure.
Is this reflectional symmetry?

5. Reflection line
Reflection line is called the line of symmetry.

6. Rotational Symmetry
Rotational symmetry—a figure has n-fold rotational symmetry if the figure can be rotated 360/n degrees about a point (where n is a positive integer) in such a way that the resulting image coincides with the original figure.

7. Point Symmetry
Point symmetry—a figure exhibits point symmetry if it can be rotated 180* about a point so that the figure coincides with its image.

8. Translational Symmetry
Translational symmetry—a figure exhibits translational symmetry if it can be translated in such a way that the image coincides with the original figure. Figures that exhibit translational symmetry necessarily repeat infinitely; we can only represent a finite part of the figure.

9. Glide Reflection
Glide-reflectional symmetry—a figure or pattern exhibits glide reflectional symmetry if it can undergo a glide reflection in such a way that the image coincides with the original figure.
Figures with glide-reflectional symmetry necessarily repeat infinitely.

11. Identify the Type of Symmetry
Identify the types of symmetry in the following pictures.

12. What is reflectional symmetry?
It can be reflected across a line in such a way that the resulting image coincides with the original figure.
What is rotational symmetry?
The figure can be rotated 360/n degrees about a point.
What is point symmetry?
It can be rotated 180* about a point so that the figure coincides with its image.
What is glide reflection symmetry?
It can undergo a glide reflection in such a way that the image coincides with the original figure.

13. Assignment
Worksheet 3-4, 3-5
p. 23, skip 6-8
p. 24, skip 6-13