Download Ratio Dilation - San Diego Unified School District

Mr. Nefalar
Geometry
Period 3&4
Rhombuses, Rectangles, and Squares
5/17/2007
Outcome: Students will be able to create scaled copies of
figures using Ratio and Parallel techniques of Dilation.
Warm Up
(12:13 -12:23) 15 mins.
In Geogebra construct a kite and a trapezoid.
Kite
Trapezoid
Yes
No
Yes
No
Are opposite angles congruent?
Are any angles congruent?
Are any angles supplementary?
(Add to 180°)
Are Diagonals congruent?
Are the intersection of
Diagonals midpoints?
Are the Diagonals
perpendicular?
Topic 1: Geogebra Investigation of Ratio Dilation
Definition
Ratio Dilation – uses a focus point next to the shape as a
center of dilation and rays from the center of dilation through
points on the figure to create scaled copies of the figure.
LA’= A’A
LE’= E’E
LD’= D’D
LC’= C’C
LB’= B’B
Scale ratio: 1:2  Dilate by 2
Standards
2,3,4,5,12,16
In Geogebra construct a triangle…
 Dialate by 2

Dialate by ½

Dialate by 3
Checkpoint


Download the Geogebra file “Ratio Dilation (2x)
o Dialate by 2
Download the Geogebra file “Ratio Dilation (.5x)
o Dialate by 1/2
Topic 2: Geogebra Investigation of Parallel Dilation
Definition
Parallel Dilation – uses a point in the middle of the shape as
a center of dilatation and rays from the center of dilation
through points on the figure to create scaled copies of the
figure.
EA = AA’
EB = BB’
LC = CC’
LD = DD’
Scale ratio: 1:2  Dilate by 2
In Geogebra construct a triangle…
 Dilate by 2
 Dilate by 1/2
 Dilate by 3
Checkpoint


Download the Geogebra file “Parallel Dilation (2x)
o Dilate by 2
Download the Geogebra file “Parallel Dilation (.5x)
o Dilate by 1/2
Exit Exam
On a piece of paper draw a triangle and demonstrate any of
the dilation techniques only using a straight edge (doesn’t
have to be a ruler).