reduction. Then find the scale factor of the dilation. 1. To start, identify whether the image is larger or smaller than
Name
Class
Date
Practice
9-6
Form K
Dilations
The dashed-line figure is a dilation image of the solid-line figure. The labeled point is the center of dilation. Tell whether the dilation is an enlargement or a reduction. Then find the scale factor of the dilation. 1. To start, identify whether the image is larger
or smaller than the preimage. Next, find the scale factor:
image length = preimage length 2.
3.
4.
5.
A dilation has center (0, 0). Find the image of each point for the given scale factor. 6. B(2, 3); D6(B)
To start, multiply each coordinate by the scale factor.
D6 (B) = (2
,3
)=(
,
)
8. U(–3, –2); D3(U)
7. C(7, 2); D3(C) 9. A(0, –5); D 2 (A)
10. G(3, 1); D–4(G)
5
11. R ( 3, 5); D1 ( R )
12.
X ( 1 , 3); D2 (X) 2
4
Prentice Hall Foundations Geometry • Teaching Resources
55
Name
9-6
Class
Date
Practice (continued)
Form K
Dilations
You look at each object described in Exercises 13–15 under a magnifying glass. Find the actual dimension of each object. 13. The image of a bug is 5 times its actual size and has a width of 1.5 cm.
image length = scale factor · actual length ? = ? · ? 14. The image of a worm is 4 times its actual size and has a length of 7 cm. 15. The image of a hair is 10 times its actual size and has a length of 0.4 cm. 16. A dilation maps ΔQRS to ΔQ′R′S′. QR = 10 in. and Q′R′ = 12 in.
If RS = 12 in., what is R′S′? 17. A dilation on a coordinate grid has center (0, 0) and scale factor 2.5. Point A is
at (3, 7). What is the y-coordinate of the image of A? 18. ΔA′B′C′ is a dilation image of ΔABC. The scale factor for the dilation is 1.25.
Is the dilation an enlargement or a reduction? 19. A square has 12-cm sides. Describe its image for a dilation with center at one
of the vertices and scale factor 0.4. 20. Graph pentagon PENTA and its image
D0.5(PENTA) = P′E′N′T′A′. The vertices of PENTA are: P(0, 4), E(6, 6), N(4, 0), T(0, –4), A(–2, 0).
A dilation maps ΔMNO onto ΔM′N′O′. Find the missing values. 21. MN = 2 in., M′N′ = 3.5 in.
22. MN = 2 cm, M′N′ = 1.6 cm
NO = 3 in., N'O' =
in.
NO = 5 cm, N'O' =
cm
MO = 4 in., M'O' =
in.
MO = 6 cm, M'O' =
cm
Prentice Hall Foundations Geometry • Teaching Resources
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