day 2 dilations.notebook
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Quiz Now coming soon....Homework p 100 16, 1012
Agenda Dec 15, 20161. Do Now2. ?s on Proportions3. Dilations
Pick up graph paper
Do Now
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Return Test
HW Questions?
SMART Notebook
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A dilation is a transformation in which a polygon is enlarged or reduced by a given scale factor r around a given center point O.
preimage: Pcenter of dilation: Oimage: P'
Notation: A dilation with center O and scale factor r, with preimage P and image P', is represented by:
DO, r (P) = P'
dilationcenter
scale factor
preimage
image
Scale Factor
Dilations
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• transformation (Dk) produces an image that is same shape as the preimage but different size
• k is the scale factor • center of the dilation is a fixed
point in the plane about which all points are transformed.
What if k is greater than 1? less than 1?
P
1) Dilate point P(3,2) about the origin by a scale factor of 3.
A B
C
2) Dilate ΔABC about the origin by a scale factor of 1/2.
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3) The image of point A after a dilation of 3 is (6, 15). What was the original location of point A?
a) (2,5)
b) (3,12)
c) (9, 18)
d) (18, 45)
4) What is the scale factor of the dilation that maps (3,6) onto (7,14)?
A
B
CO
A'
B'
C'
1) What is the measure of A'B'C?
2) What is the relationship between AB & A'B' and BC & B'C'?
Let's look at this transformation....
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O
A B
A' B'
1) Are rays AB and A'B' parallel to each other?
2) Do ray AB and A'B' point in the same direction?
Let's look at this transformation....
Use the picture below to answer the following questions.
a) Dilate AB about the origin Oby a scale factor of 2.
b) If AB=5, find A'B'.
c) If AO =3, find A'O.
d) If B'O=8, find BO.
A
B C
O
A'
C'B'
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P
Describe the relationship between circle P and circle P'.
1) What is the radius of circle P?
2) What is the radius of circle P'?
3) What is the relationship between the radii circle P and circle P'?
Do you think a dilation is a rigid motion? Why or why not?
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Attachments
test unit 4 answers.pdf
SMART Notebook
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