Bell Ringer

Dilations

Dilation

Identify DilationsExample 1

Tell whether the dilation is a reduction or an enlargement.b.

SOLUTION

a. The dilation is an enlargement because the image (P'Q'R') is larger than the original figure (PQR).

a.

b. The dilation is a reduction because the image (X'Y'Z' ) is smaller than the original figure (XYZ).

b. scale factor = CP

CP'=

3

6= 2

Find Scale FactorsExample 2

Find the scale factor of the dilation.a.

b.

SOLUTION

Find the ratio of CP' to CP.

a. scale factor = CP

CP'=

3

2

Now You Try Identify Dilations and Find Scale Factors

Tell whether the dilation is a reduction or an enlargement. Then find the scale factor of the dilation.

1.

2.

3.

enlargement; 2ANSWER

ANSWER reduction; 31

ANSWER reduction;73

Dilations and Similar FiguresExample 3

P'Q'R' is the image of PQRafter a reduction.Find the value of x.

14

8=

x6 Substitute 8 for CP', 14 for CP, 6

for Q' R', and x for QR.

8 · x = 14 · 6 Cross product property

SOLUTION

Write a proportion.CP

CP'=

QR

Q'R'

8x = 84 Multiply.

x = 10.5 Divide each side by 8.

Checkpoint Dilations and Similar Figures

The red figure is the image of the blue figure after a dilation. Find the value of the variable.

4.

ANSWER 5

5.

ANSWER 2

Now You Try

Page 396 Complete 2-28 even only

On a separate sheet of paper complete quiz 2 on page 398