1
Unit 4
Similarity and Transformations
Day 1 Dilations
Complete your 1/2 sheet bellringer!
10 minutes.
2
Agenda
∙ Bellringer
∙ Review Bellringer
∙ Intro to Dilations and Similarity
> Notes on Guided Notes
∙ I do/We Do
> Notes on Guided Notes
∙ Group Work
> On Worksheet
∙ Closing
10 minutes
5 Minutes
15 minutes
20 minutes
35 Minutes
5 Minutes
3
Today, I will
1. Learn and Apply Properties of dilations of lines
2. Draw the dilation of a line
3. Identify the scale factor given a dilation
4. Draw the dilation of a line segment and shapes
5. Learn and Apply Properties of dilations of line segments
6. Identify scale factor given the dilation of line segment
7. and use scale factor to find lengths of dilations of line segments
4
5
I Do We Do
Judith says that any line can be
mapped onto any other line by a
dilation with center O. Is Judith
Correct? Explain.
In the figure below, line q is the image of line
r under a dilation with center O, and line s is
the image of line t under a dilation with center
O. What can you conclude about
quadrilateral ABCD? Justify your conclusion.
A B
CD
o
6
I Do We DoThe line y = 3x + 4 is dilated by a factor of 0.2
with the center at the origin. Graph the line and
its dilated image on the same set of axes.
Compare the original line to its dilation.
A line represented by the equation y = 4x is
dilated by a scale factor of 1.2 about the origin.
Graph the line y = 4x and its dilation. Write the
equation of the new line. What is the
relationship between the lines?
7
I Do We Do
Line r' is the dilation of line r. Find the
scale factor, k, of the dilation if the origin is
the center of the dilation.
Find the scale factor of the dilation
applied to l that results in l'. The dilation is
centered at the origin.
8
I Do We DoSegment R'S' is the result of a dilation of
segment RS. The dilation was centered at the
origin and has a scale factor of 1/2. Graph
segment RS and explain how you obtained your
answer.
Draw the image of the given figure after a
dilation with center O and a scale factor of 1/3.
9
We Do
Examine the figure shown below.
A. A dilation, centered at the origin with a
scale factor of 1.5 is applied to segment
AB. Find the length of the resulting line
segment A'B'. Show your work.
B. Find the length of A'B' after a dilation
centered at the origin with a scale factor of
3. Did you use any information from Part A
to solve Part B? Explain.
C. What dilation would start with segment
A'B' in Part B and result in the original
segment AB? Write a generalization for
undoing a dilation of scale factor k.
10
Recommended
