February 07, 2017
Dilations
Dilation: a transformation that moves each point along the ray
through the point, starting from a fixed center, and multiplies
distances from the center by a common scale factor.
WOAH!! What does that mean??
When we dilate something we make it ______________ or
_________________.
When we dilate a figures, we enlarge or reduce the image by a set
amount, the _______________________.
We always dilate around a fixed center, usually the __________.
What changes in a dilation?
What stays the same?
February 07, 2017
The ___________________ tells us by how much we need to
reduce or enlarge the image.
Scale factor: the ratio of a length in the image to the
corresponding length in the preimage. Sometimes written as ____.
Scale factor:
Which is the preimage? _________ How long is side DG? ______
Which is the image? __________ How long is side DG? ______
Write the scale factor.
This means that the image is _________ times the size of the
preimage.
Try it pg. 334, part 1.
February 07, 2017
Dilate to
ENLARGE
Step 1: Identify the coordinates of each vertex of the preimage.
Step 2: Multiply each x and y value by the _________________.
Write the new coordinates.
Step 3: Graph the new image.
A dilation with a scale factor greater than 1 is called an
_________________________ because the image is larger than
the preimage.
Preimage
xr
Image
P(
)
x
P'(
)
Q(
)
x
Q'(
)
R(
)
x
R'(
)
February 07, 2017
Dilate to REDUCE
Step 1: Identify the coordinates of each vertex of the preimage.
Step 2: Multiply each x and y value by the _________________.
Write the new coordinates.
Step 3: Graph the new image.
A dilation with a scale factor between 0 and 1 is called a
_____________________ because the image is smaller than
the preimage.
Preimage
xr
Image
P( 0,0 )
x
P'(
)
H( 9,0 )
x
H'(
)
O( 9,6 )
x
O'(
)
T( 0,6 )
x
T'(
)
Try it, pg. 335
pg. 336