Transcript Document

Materials
Reminders
Get out your agenda if you see
your name below. I would like
to have you in my FLEX
Wednesday.
Period 2
Period 7
Determine whether the following
polygons are similar.
4
4
6
6
2
3
4-7 Dilations
How do I graph dilations on a
coordinate plane?
Important
Vocabulary
Dilation– the image produced by enlarging or
reducing a figure
Center – a fixed point used for measurement
when altering the size of an image
Questions:
How do I find
the coordinates
for a new,
dilated figure?
Notes:
Complete the following table by substituting the scale
factor for the variable, a.
hint: just multiply all of the coordinates by the scale factor
Original
Coordinates
Relationship
D(2,0)
(2 x a, 0 x a)
C(2,2)
(2 x a, 2 x a)
B(0,1)
(0 x a, 1 x a)
A(0,0)
(0 x a, 0 x 2)
New Image
Coordinates
Drawing Dilations
1. Use the provided graph paper to draw
dilations of the provided figures.
Graphing Dilations
1. Use the provided graph paper to draw
dilations of the provided figures.
Questions:
How do I find
and classify a
scale factor?
Notes:
Steps
1. Write a ratio of the x or y-coordinate of one vertex of
the dilation (NEW figure) to the x or y-coordinate of
the original (OLD) figure.
Example:
Vertex of Original Figure
Corresponding Vertex of
Dilated (NEW) Figure
(2,3)
(6,9)
6
=3
2
The Scale Factor is 3
If the scale factor is greater than one the dilation is and
ENLARGEMENT
If the scale factor is less than one the dilation is a
REDUCTION
Homework
Page 228-229; 7-16 and
20
AND Cornell Notes
Summary