DILATIONS ON AND OFF CENTER
SIMILARITY
TODAY’S OBJECTIVE: YOU WILL BE ABLE TO DILATE OBJECTS IN THE COORDINATE
PLANE WITH THE CENTER OF DILATION BEING THE ORIGIN OR SOME OTHER GIVEN
POINT.
Dilating an object centered at the origin is quite easy. You simply multiply each x and y
coordinate of every point of your object by the scale factor (k) given. Let us take a look at some
examples below.
Dilate the object to the right by a scale factor of 1/2.
Graph the triangle SAT with coordinates S(1,1), A(2,3)
T(3,1). Then dilate the triangle by a scale factor of 2.
DILATIONS ON AND OFF CENTER
SIMILARITY
Dilations not centered at the origin! Kinda tough so let’s focus in!
Dilate the object to the right with a center of a dilation
(-1,2) and a scale factor ½ .
Draw and state the coordinates of the image below after a dilation with a scale factor of 2
with the center of dilation as point (6, 4).
RULE! 1) Translate COD back to origin.
2) Distribute the scale factor through everything
3) Translate back to COD
DILATIONS ON AND OFF CENTER
Find the rule for (x,y) with a center of dilation of (5,-3) and scale factor of k=2
Find the rule (x,y) with a center of dilation of (-4,6) and a scale factor of k=1/2.
Group work:
SIMILARITY
DILATIONS ON AND OFF CENTER
SIMILARITY
Center of dilation (-4,-4)
1) Find a coordinate rule for the dilation with center (2, –1) and
scale factor 3.
2) Find a coordinate rule for the dilation with center (6, –9) and
scale factor 1/3.
3)
DILATIONS ON AND OFF CENTER
HW HELP: Use this for #7 on your HW
SIMILARITY