Exercise 29 Page 213

To find the scale factor

k,

we need to calculate the ratio between the image and the preimage.

scale factor = \frac{image length}{preimage length}

The image is what we have after the dilation. In this case, the image is a dilated photo with a dimension of

5 inches

by

7 inches .

The preimage, which in this case is the original photo, has a dimension of

2.5 inches

by

3.5 inches .

To calculate

k,

we can substitute either pair of the corresponding sides. Let's choose the shorter ones.

k = \frac{5}{2 . 5}

$\frac{a}{b} = \frac{a \cdot 2}{b \cdot 2}$

k = \frac{1 0}{5}

Calculate quotient

k = 2