1. Make your new weekly Warm up Page
January 23-27, 2017
Monday Jan. 23
WRITE ON SHEET
“warm up on daily notes”
Do warm up on daily notes

2. Agenda:
Warm up
Week ahead…TEST FRIDAY
Standard / I Can
Lesson
Exit ticket
Problem set

3. Standard: 8.G.A.3 Describe the effect of dilations, translations, rotations, and reflections on a two dimensional figures using coordinates.
I CAN…. describe what happens when two dimensional figures are dilated using coordinates.

4. Vocabulary
dilation
center of dilation
scale factor

5. Your pupils are the black areas in the center of your eyes
Your pupils are the black areas in the center of your eyes. When you go to the eye doctor, the doctor may dilate your pupils, which makes them larger.
A dilation is a transformation that changes the size, but not the shape, of a figure.

6. Every dilation has a fixed point that is the center of dilation
Every dilation has a fixed point that is the center of dilation. To find the center of dilation, draw a line that connects each pair of corresponding vertices. The lines intersect at one point. This point is the center of dilation.

7. Example 1
Tell whether each transformation is a dilation. Explain.
Compare the ratios of
corresponding side lengths. 2 6 1 3 BC
B'C' = 2 6 1 3 AD
A'D' =
Yes; the ratios of
corresponding side length
are equal and
corresponding angles are
congruent.

8. Example 2
Tell whether each transformation is a dilation. Explain.
Compare the ratios of
corresponding side lengths. 4 2 BA
B'A' =
= 2 5 3 AC
A'C' =
1.66
No; the ratios of
corresponding side
length are not equal.

9. The scale factor describes how much a figure is enlarged or reduced
The scale factor describes how much a figure is enlarged or reduced. It represents the ratio of a length on the image to the corresponding lentth on the original figure.

10. Example 3
Dilate the figure below by a scale factor of 2. What are the vertices of the image?
Multiply the coordinates by 2 to find the vertices of the image.
A’B’C’
ABC
A(2, 2) A’(2  2, 2  2) A’(4, 4)
B(3, 4) B’(3  2, 4  2) B’(6, 8)
C(5, 2) C’(5  2, 2  2) C’(10, 4)
The vertices of the image are A’(4, 4), B’(6, 8), and C’(10, 4).

11. Example 4
Dilate the figure below by a scale factor of . What are the vertices of the image?
1 3
Multiply the coordinates by to find the vertices of the image.
1 3
A’B’C’
ABC
A(3, 9) A’(3  , 9  ) A’(1, 3)
1 3
B(9, 6) B’(9  , 6  ) B’(3, 2)
1 3
C(6, 3) C’(6  , 3  ) C’(2, 1)
1 3
The vertices of the image are A’(1, 3), B’(3, 2), and C’(2, 1).

12. Example 5
Dilate the figure by a scale factor of 2. What are the vertices of the image? 2 4 6 8 10 C A B 2 4 6 8 10

13. A’B’C’
ABC
A(2, 2) A’(2  2, 2  2) A’(4, 4)
B(4, 2) B’(4  2, 2  2) B’(8, 4)
C(2, 4) C’(2  2, 4  2) C’(4, 8)
The vertices of the image are A’(4, 4), B’(8, 4), and C’(4, 8).

14. 10 B’ C’ A’ 8 6 C 4 2 A B 2 4 6 8 10

15. Example 6
Dilate the figure by a scale factor of What are the vertices of the image? 10 C 8 6 A B 4 2 2 4 6 8 10

16. A’B’C’
ABC
A(4, 5) A’(4  0.5, 5  0.5) A’(2, 2.5)
B(8, 5) B’(8  0.5, 5  0.5) B’(4, 2.5)
C(4, 9) C’(4  0.5, 9  0.5) C’(2, 4.5)
The vertices of the image are A’(2, 2.5), B’(4, 2.5), and C’(2, 4.5).

17. 10 C 8 6 B’ C’ A’ A B 4 2 2 4 6 8 10

18. Exit Tiecket 3. Identify the transformation that is a dilation.
A. A(0, 3), B(4, 4), C(2, 2)  A’(0, 9), B’(12, 12), C’(6, 6)
B. A(2, 3), B(3, 5), C(5, 7)  A’(5, 6), B’(6, 8), C’(8, 10)
C. A(5, 2), B(3, 7), C(7, 9)  A’(2, –1), B’(0, 4), C’(4, 6)
D. A(1, 2), B(3, 4), C(5, 6)  A’(4, 5), B’(6, 7), C’(8, 9)
Tell whether the transformation is a dilation. explain
Explain.‏
2. A triangle has vertices A'(2,4), B(5,6), and C(6,1). Dilate the figure by a scale factor of 2 with the origin as the center of dilation. What are the vertices of the image?

19. Student.demos.com Class code:RGQ65 19 19