1. 12-7
Dilations
Warm Up
Lesson Presentation
Lesson Quiz
Holt Geometry

2. Warm Up
1. Translate the triangle with vertices A(2, –1), B(4, 3), and C(–5, 4) along the vector <2, 2>.

3. Objective
Identify and draw dilations.

4. Vocabulary
center of dilation
enlargement
reduction

5. Note 32
A dilation is a transformation that changes the size of a figure but not the shape. The image and the preimage of a figure under a dilation are similar.

6. Example 1: Identifying Dilations
Tell whether each transformation appears to be a dilation. Explain. A. B.
No; the figures are not similar.
Yes; the figures are similar and the image is not turned or flipped.

7. Check It Out! Example 1
Tell whether each transformation appears to be a dilation. Explain. a. b.
Yes, the figures are similar and the image is not turned or flipped.
No, the figures are not similar.

8. Do Not Copy!!

9. A dilation enlarges or reduces all dimensions proportionally
A dilation enlarges or reduces all dimensions proportionally. A dilation with a scale factor greater than 1 is an enlargement, or expansion. A dilation with a scale factor greater than 0 but less than 1 is a reduction, or contraction.

10. Check It Out! Example 4
Draw the image of the triangle with vertices R(0, 0), S(4, 0), T(2, -2), and U(–2, –2) under a dilation centered at the origin with a scale factor of