Warm Up

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Warm Up
Problem of the Day
Lesson Presentation
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Warm Up Multiply. 1. 4 ? 2. 12 ? 3. 24 ?
4. 36 ?
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3
18
27
10
30
5. 4 ? 2.5 6. 12 ? 2.5
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Problem of the Day Every day, a plant grows to
three times its size. Every night, it shrinks to
half its size. After three days and nights, it is
6.75 in. tall. How tall was the plant at the
start?
2 in.
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Learn to identify and create dilations of plane
figures.
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Vocabulary
dilation
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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.
Translations, reflections, and rotations are
transformations that do not change the size or
shape of a figure. A dilation is a transformation
that changes the size, but not the shape, of a
figure. A dilation can enlarge or reduce a figure.
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Additional Example 1 Identifying Dilations
Tell whether each transformation is a dilation.
D.
C.
The transformation is not a dilation. The
figure is distorted.
The transformation is a dilation.
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Check It Out Example 1
Tell whether each transformation is a dilation.
A.
B.
The transformation is not a dilation. The
figure is distorted.
The transformation is a dilation.
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Check It Out Example 1
Tell whether each transformation is a dilation.
D.
C.
The transformation is not a dilation. The
figure is distorted.
The transformation is a dilation.
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Additional Example 2 Dilating a Figure
Dilate the figure by a scale factor of 1.5
Multiply each side by 1.5.
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Check It Out Example 2
Dilate the figure by a scale factor of 0.5 with G
as the center of dilation.
G
2 cm
2 cm
F
H
2 cm
Multiply each side by 0.5.
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Insert Lesson Title Here
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Additional Example 3A Using the Origin as the
Center of Dilation
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.
The vertices of the image are A(8, 16), B(6,
4), and C(10, 4).
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Additional Example 3B Using the Origin as the
Center of Dilation
Dilate the figure below by a scale factor of .
What are the vertices of the image?
The vertices of the image are A(1, 3), B(3, 2),
and C(2, 1).
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Check It Out Example 3A
Dilate the figure by a scale factor of 2. What
are the vertices of the image?
10
8
6
C
4
2
A
B
8
10
2
4
6
0
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Check It Out Example 3A Continued
The vertices of the image are A(4, 4), B(8, 4),
and C(4, 8).
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Check It Out Example 3A Continued
10
8
6
C
4
2
B
A
8
10
2
4
6
0
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Check It Out Example 3B
Dilate the figure by a scale factor of 0.5. What
are the vertices of the image?
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C
8
6
B
A
4
2
8
10
2
4
6
0
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Check It Out Example 3B Continued
The vertices of the image are A(2, 2.5), B(4,
2.5), and C(2, 4.5).
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Check It Out Example 3B Continued
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C
8
6
B
A
4
2
8
10
2
4
6
0