Download line of symmetry

April 21st
- Your next hand-in day will be Wednesday, April 30th -
Draw 5 2D Shapes.
Using a dotted line, draw a line of
symmetry through each shape.
Do any of your shapes have more than
one line of symmetry?
- Similarity, Transformations, & Symmetry Approximately April 21st to May 14th
This unit will help you develop an
understanding of the Geometry of 2D
Shapes.
Geometric understanding is formally used
in careers like architecture, engineering,
design, & surveying.
We will learn how to work with:
- Scale Diagrams
- Similar Shapes
- Line Symmetry & Rotational Symmetry
As a group, review the flags of the
provinces/territories in Canada.
Which one(s) have lines of symmetry?
What Is Line Symmetry?
- There is/are a line(s)
that divide the shape
into two congruent
parts
- Called the line of
symmetry or line of
reflection
- They can have more
than one line of
symmetry!
What Is Line Symmetry?
- It DOES NOT mean
that the line simply
cuts a shape in half
- Each side has to be
exactly the same
- If they folded on top of
another, it would be a
perfect match
On the worksheet, Master 7.19:
- Identify how many lines of symmetry
each shape has
One the back of the worksheet:
- Sort the shapes according to the
number of lines of symmetry that they
have
- Which shapes do not have any lines of
symmetry?
Which shapes have 1 line of symmetry?
A, D, G, I
Which shapes have 2 lines of symmetry?
B
Which shapes have 3 lines of symmetry?
None
Which shapes have 4 lines of symmetry?
F, H
Which shapes have no lines of symmetry?
C, J, K
Symmetrical Logos!
You and a partner are designing a logo for
(insert interesting idea here).
Your logo must include:
- 5 shapes that have their own unique lines
of symmetry
- Overall symmetrical design
- At least 3 different colours
April 22nd
- Your next hand-in day will be Wednesday, April 30th -
How many lines of symmetry do each of
these hazard symbols have?
Example ONE
What lines of symmetry exist in each
tessellation below?
Example ONE
What lines of symmetry exist in each
tessellation below?
Example TWO
Which triangles are
related to the
red triangle
by a line of
reflection?
Example TWO
Which triangles are
related to the
red triangle
by a line of
reflection?
Example THREE
Shape ABCD is part
of a larger shape.
If line AD serves as
a line of symmetry,
draw the remaining
portion of the
shape.
Example THREE
Shape ABCD is part
of a larger shape.
If line AD serves as
a line of symmetry,
draw the remaining
portion of the
shape.
Line Symmetry Questions
Page 358, Questions 4-6
Page 359, Questions 9-10
April 23rd
- Your next hand-in day will be
Wednesday, April 30th -
How many lines of
symmetry does
each logo have?
April 28th
- Your next hand-in day will be
Wednesday, April 30th -
How many lines of
symmetry does
each logo have?
April 29th
- Your next hand-in day will be
Wednesday, April 30th -
How many lines of
symmetry does
each logo have?
April 30th
- Hand-In Day-
How many
lines of
symmetry does
each logo
have?
May 5th
- Your next hand-in day is Tuesday, May 13th -
Maps usually feature a Scale Factor like the one
displayed below.
Use the image to describe what the Scale Factor is
telling us.
- A Scale Diagram is an
image that is an
enlargement or
reduction of another
image
- Enlargement = bigger
- Reduction = smaller
You have been handed a picture of a 2D
or 3D shape, with measurements.
Find a person in the classroom who has
the same shape as you, but the image
has been enlarged or reduced.
6cm
3cm
2cm
4cm
Scale Factors
- To determine how
much an image is
enlarged or reduced
by, use the following
formula:
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐧 𝐬𝐜𝐚𝐥𝐞 𝐝𝐢𝐚𝐠𝐫𝐚𝐦
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐧 𝐨𝐫𝐢𝐠𝐢𝐧𝐚𝐥 𝐝𝐢𝐚𝐠𝐫𝐚𝐦
- Scale > 1
Enlargement
- Scale < 1
Reduction
Length of vertical
segment on the scale
diagram
=
Length of vertical
segment on the original
diagram
=
Length of horizontal
segment on the scale
diagram
=
Length of horizontal
segment on the original
diagram
=
Scale Factors
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐧 𝐬𝐜𝐚𝐥𝐞 𝐝𝐢𝐚𝐠𝐫𝐚𝐦
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐧 𝐨𝐫𝐢𝐠𝐢𝐧𝐚𝐥 𝐝𝐢𝐚𝐠𝐫𝐚𝐦
- The scale factor of the
5
image is or 2.5
2
Scale Factors
- A mosquito measures
12mm in length
- A newspaper picture
of a mosquito
measures 4.5cm in
length
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐧 𝐬𝐜𝐚𝐥𝐞 𝐝𝐢𝐚𝐠𝐫𝐚𝐦
𝐋𝐞𝐧𝐠𝐭𝐡 𝐨𝐟 𝐨𝐫𝐢𝐠𝐢𝐧𝐚𝐥
Scale Factors
- A mosquito measures
12mm in length
- A newspaper picture
of a mosquito
measures 4.5cm in
length
𝟒𝟓𝐦𝐦
𝟏𝟐𝐦𝐦
Scale Factors
- An image measured
9cm by 6cm
- It needs to be
enlarged by a scale
factor of:
𝟕
𝟐
- What dimensions will
the enlargement
have?
Scale Factors
- An image has the
measurements seen
here 
- It needs to be
enlarged by a scale
factor of:
1.5
- What dimensions will
the enlargement
have?
Scale Factors
- An image has the
measurements seen
here 
- It needs to be
reduced by a scale
factor of:
0.25
- What dimensions will
the reduction have?
Scale Factor Questions
Pg 323
Pg 329
Qs 4, 5, 11
Qs 5, 7, 12
May 6th
- Your next hand-in day is Tuesday, May 13th -
Draw a 2D shape that has a rotational symmetry
with an order of 6.
Label the measurements of your shape.
Enlarge your shape by a scale factor of 4.5.
Scale Factor Word Problems
Complete the questions provided on the
worksheet.
Place all answers on a piece of loose
leaf & remember to include diagrams!
May 7th
- Your next hand-in day is
Tuesday, May 13th -
You are provided with
the following shape:
If it is to be reduced
by a scale factor of
3/4, what will its new
measurements be?
Draw & label a
diagram of the
reduction.
Similarity
- Two triangles are
similar if the only
difference is:
- Size
- Rotation
- All of the triangles in
the image to the right
are considered
similar
Similar Triangles. (Accessed 2014). Uploaded by Math is Fun. Available online at:
http://www.mathsisfun.com/geometry/triangles-similar.html
Similarity
- Similar triangles have
to have:
- All of their angles
equal
OR
- Corresponding
sides have the
same ratio (they
are scale diagrams
of one another)
Similar Triangles. (Accessed 2014). Uploaded by Math is Fun. Available online at:
http://www.mathsisfun.com/geometry/triangles-similar.html
Representing Similar
Triangles
- The symbol ∠ is used
to represent angle
- These 2 triangles are
similar because:
∠ A = ∠ Q = 75o
∠ B = ∠ R = 62o
∠ C = ∠ P = 43o
Representing Similar
Triangles
- When comparing 2
triangles, order the
letters to match the
angles:
(ex) ∆ABC ~ ∆QRP
- AB matches QR
- BC matches RP
- AC matches QP
Similar Triangles
Identify how the 2 triangles are similar
Similar Triangles
How tall is the totem pole to
the nearest tenth of a
meter?
Similar Triangles
Page 349-351
Qs 4-7, 9-12
May 12th
- Your next hand-in day is
Tuesday, May 13th -
You are provided with
the following shape:
If it is to be reduced
by a scale factor of
3/4, what will its new
measurements be?
Draw & label a diagram
of the reduction.
May 13th
- Hand-In Day!! April 30th - Today -
Use similar triangles to find the value of x.