1. Similarity Transformations
Advanced Geometry

2. Transformation
A transformation is an operation that maps an original figure, the preimage, onto a new figure called the image.

3. Similarity Transformations
A dilation is a transformation that enlarges or reduces the original figure proportionally.

4. Same Shape But Different Size
Dilation
Same Shape But Different Size

5. Dilations
Dilations are preformed with respect to a fixed point called the center of dilation.
The scale factor of a dilation describes the extent of the dilation.
The scale factor is the ratio of a length on the image to a corresponding length on the preimage.
The letter k usually represents the scale factor of a dilation. The value of k determines whether the dilation is an enlargement or reduction.

6. Dilation Notation

7. Location of the center of dilation

8. Enlargement
A dilation with a scale factor greater than 1 produces an enlargement, or an image that is larger than the original figure.

9. Reduction
A dilation with a scale factor between 0 and 1 produces a reduction, or an image that is smaller than the original figure.

10. Enlargement vs Reduction

11. What if k = 1?

12. Example
Determine whether the dilation from A to B is an enlargement or a reduction. Then find the scale factor of the dilation.

13. Example
Determine whether the dilation from A to B is an enlargement or a reduction. Then find the scale factor of the dilation.

14. Example
Determine whether the dilation from A to B is an enlargement or a reduction. Then find the scale factor of the dilation.

15. Example
The dimensions of a regulation tennis court are 27 feet by 78 feet. The dimensions of a table tennis table are centimeters by 274 centimeters. Is a table tennis table a dilation of a tennis court? If so, what is the scale factor? Explain.

16. Work backwards to find the center of dilation, and also determine the scale factor.

17. Work backwards to find the center of dilation, and also determine the scale factor.