1. 9.1 Translations
-Transformation: a change in the position, shape, or size of a geometric figure
-Preimage: the original figure
-Image: the resulting figure
-Isometry: when the original figure and resulting figure are congruent
-Composition: a combination of 2 or more transformations

2. 9.1 Translations
-Translation: an isometry that maps all points of a figure the same distance in the same direction

3. 9.2 Reflections
-Reflection: an isometry in which a figure and its image have opposite orientations

4. 9.3 Rotations
-Rotation: need the center of rotation (point), the angle of rotation (positive degree measure), and if the rotation is clockwise or counterclockwise

5. Symmetry
-Symmetry: if there is an isometry that maps a figure onto itself
- Reflectional Symmetry: if the isometry is the reflection of a plane figure
-Rotational Symmetry: if the isometry of a preimage is the image after a rotation of 180*

6. 9.4 Compositions of reflections
-Theorem 9.1: A translation or rotation is a composition of 2 reflections
-Theorem 9.2: A composition of reflections across 2 parallel lines is a translation
-Theorem 9.3: A composition of reflections across 2 intersecting lines is a rotation
-Theorem 9.4: In a plane, 1 of 2 congruent figures can be mapped onto the other by a composition of at most 3 reflections
-Glide Reflection: the composition of a translation and a reflection across a line parallel to the direction of translation
-Theorem 9.5: there are only 4 isometries:
Reflection Translation Rotation Glide Reflection

7. 9.6 Dilation
-Dilation: a transformation whose preimage and image are similar
-Enlargement: a dilation if the scale factor is greater than 1
-Reduction: a dilation if the scale
factor is less than 1

8. Tesselations
-Tesselation: a repeating pattern of figures that completely covers a plane, without gaps or overlaps. You can make tesselations with translations, rotations, and reflections
-Theorem 9.6: every triangle tessellates
-Theorem 9.7: every quadrilateral tessellates