1. Dilations on the Coordinate Plane

2. Dilations on the Coordinate Plane
Enlarging or reducing a figure is called a dilation
A dilated figure is similar to the original figure
The ratio of the new figure to the original is called a scale factor

3. Dilations on the Coordinate Plane
If triangle ABC is dilated by scale factor of 2, triangle A’B’C’ will have sides twice as big as triangle ABC
If triangle ABC is dilated by scale factor of 4, triangle A’B’C’ will have sides four times the size of triangle ABC

4. Dilation Mini-Lab In this lab you will…
Graph square MATH with vertices at M(-2, 2), A(2, 2), T(2, -2) and H(-2, -2)
Then dilate the figure by a scale factor of 3
To find the vertices of the dilation, multiply each coordinate in the ordered pairs by the scale factor (3)

5. Dilation Mini-Lab
Graph square MATH with vertices at M(-2, 2), A(2, 2), T(2, -2) and H(-2, -2)
M A
H T

6. Dilation Mini-Lab
To find the vertices of the dilation, multiply each coordinate in the ordered pairs by the scale factor (3)
M (-2 , 2) A (2 , 2) T (2 , -2) H (-2 , -2)
x3 x x3 x x3 x x3 x3
M’(-6 , 6) A’(6 , 6) T’(6 , -6) H’(-6 , -6)

7. Dilation Mini-Lab
Graph square M’A’T’H’ with vertices at M’(-6, 6), A’(6, 6), T’(6, -6) and H’(-6, -6)
M’ A’
H’ T’
M A
H T

8. Dilation Mini-Lab
To check your graph, draw lines through the origin and each of the vertices of the original figure
If the vertices of the dilated figure don’t lie on the same lines you’ve made a mistake
M’ A’
H’ T’
M A
H T

9. Dilation Mini-Lab
What do you think happens if you dilate a figure to a scale factor of 1?
Multiply each coordinate in triangle ABC with vertices A(2, 12), B(12, 4), and C(20, 20) by a scale factor of 1
What do you notice?
The coordinates stay the same!

10. Dilation Mini-Lab
What do you think happens if you dilate a figure to a scale factor of ½ ?
On graph paper, graph triangle ABC with vertices A(2, 12), B(12, 4), and C(20, 20)
Multiply each coordinate in triangle ABC by a scale factor of ½
Graph triangle A’B’C’
What do you notice?
Triangle A’B’C’ has sides half the size of triangle ABC!

11. Dilation Checkpoint
What are the coordinates of Point A’ if Point A (3, 7) were dilated to a scale factor of 4?
What are the coordinates of Point A’ if Point A (3, 7) were dilated to a scale factor of 10?
What is the length of line segment A’B’ if an 8” line segment AB were dilated to a scale factor of 3?
A’ (12, 28)
A’ (30, 70)
24 Inches

12. Homework Practice Worksheet 9-8 (both sides) Due Tomorrow!
Review is scheduled for Tomorrow and the Coordinate Plane Test is scheduled for FRIDAY!.
Study for the test!!!