98 Transformation Geometry Dilations

Transformation Geometry
Dilations


What is a Dilation?


Dilation is a transformation that produces a
figure similar to the original by proportionally
shrinking or stretching the figure.

Dilated PowerPoint Slide


Proportionally

Let’s take a look…

And, of course, increasing the
circle increases the diameter.

 When

a figure is dilated, it must be
proportionally
largera or
smaller
So,
we always have
circle
with a

than thediameter.
original. We are just
certain
Decreasingchanging
the size of the circle
the
size
or
scale.
We have a circle with a
decreases the diameter.
certain diameter.

 Same

shape, Different scale.


Which of these are dilations??

A
HINT: SAME SHAPE, DIFFERENT SIZE

D

C


Scale Factor and Center of
Dilation

When we describe dilations we use the terms scale factor and
center of dilation.



Scale factor
Center of Dilation

Here we have Igor. He is 3 feet
tall and the greatest width
across his body is 2 feet.
He wishes he were 6 feet tall with
a width of 4 feet.

His center of dilation would be where the length and greatest width of
body intersect.
Hehis
wishes
he were larger by a

scale factor of 2.


Scale Factor




If the scale factor is larger than 1, the figure is
enlarged.

If the scale factor is between 1 and 0, the figure is
reduced in size.

Scale factor > 1
0 < Scale Factor < 1


Are the following enlarged or reduced??

C

A

Scale factor of 1.5

D
Scale factor of 0.75

Scale factor of 1/5

Scale factor of 3


The Object and the Image
B’





The original figure is
called the object and
the new figure is called
the image.
The object is labeled
with letters.
The image may be
labeled with the same
letters followed by the
prime symbol.

Image

C’

A’

B

Object
A

C


Dilations Used Everyday


Remember




Dilations are enlargements or reductions.
What are some things that you would not
mind dilating to make larger or smaller?

Practice Dilation Quiz