4

\(\triangle ABC\) is mapped to \(\triangle A’B’C\) by a dilation. What is the scale factor?

Since the image is smaller than the preimage, scale factor k > 1.

\(\frac {Image\; length}{Preimage\; length} \) = k

Example: \(\frac {A'C'}{AC}\) = k

5

\(\triangle ABC\) is mapped to \(\triangle A’B’C\) by a dilation. What is the scale factor?

Scale factor, k = \( \frac {A'C'}{AC}\) = \(\frac 36\) = \(\frac 12\)

Scale factor, k = \( \frac {B'C'}{BC}\) = \(\frac {5}{10}\) = \(\frac 12\)

Since the image is smaller than the preimage, 0 < scale factor k < 1.

\(\frac {Image\; length}{Preimage\; length} \) = k

Example: \(\frac {B'C'}{BC}\) = k