Dilations : nonrigid transformation in which the
image and preimage are similar
* could be an enlargement or reduction
scale factor (k): ratio comparing the image to pre-image
k=
Image
Preimage
If 0 < k < 1 then ________________
k = 1 then ________________
k > 1 then ________________
1. Identify the dilation as an enlargement or reduction
and give the scale factor.
P
P'
C
center of dilation
If P(x,y) is the preimage of a dilation with scale factor, k, then
P'(kx,ky) is the image.
2. Draw the image of ABC with dilation with k =
1
2
A(0,0)
B(10,0)
C(7,8)
C
A
B
3. Compare the perimeter of
4. Compare the area of
A'B'C' to
A'B'C' to
ABC.
ABC.
Construction
Draw the image of ABC under a dilation with center P and
scale factor 2.
A
P
B
C
Find the center of dilation.