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The first three letters of your name
 Can you fold the letters in a way that
the top half exactly covers the bottom
half?
 If you can draw a line !
Symmetry in Letters !
Symmetry
What is Symmetry?
 If a shape can be folded in half so that one
half fits exactly on top of the other, than we
say that the shape has got line symmetry.
 The fold is called a line of symmetry, it divides
the shape into two equal parts!
 The lines of symmetry may be vertical,
horizontal or diagonal
1 LoSOne Line of Symmetry
Vertical lines of
symmetry
Horizontal lines of
symmetry
Diagonal lines of
symmetry
RectangleThe Rectangle Problem
A rectangle has only 2 lines of symmetry and not 4 like the square

To see this consider the following:
Half a rectangle
Mirror Line
The Rectangle Problem
A rectangle has only 2 lines of symmetry and not 4 like the square

To see this consider the following:
Half a rectangle
Mirror Line
A reflection in the diagonal
would produce a kite!
Regular
Regular Polygons
Equilateral Triangle Square Regular Pentagon
Regular Hexagon Regular Octagon
Regular polygons
have lines of
symmetry equal to
the number of
sides/angles that
they possess.
Identify the Lines of Symmetry
Identify the Lines of Symmetry
Identify the Lines of Symmetry
Symmetry in Real Life
 God made many things in nature symmetrical!
 Humans like to follow Gods footsteps when
making objects because in this way things look
nicer !
How many ?
 An object may have
One line of Symmetry
Many lines of Symmetry
No lines of Symmetry
A circle ?
INFINITE LINES OF SYMMETRY !
Mix 1
How many lines of symmetry for each shape?
4 3
5 8
5
Formula one Book
Pg 49 No. 1 and No.2
Get square mirror again
HAPPY WEEKEND!
Mix 3
2 5 3
2 4
How many lines of symmetry for each shape?
Mix 4
How many lines of symmetry for each shape?
6 2 4
1 2 1
Mix 5
How many lines of symmetry for each shape?
1 2 4
5 3
Tracing 1
Reflections
object
Mirror Line
Reflect the object
shape in the mirror line
shown.
object
Mirror Line
Reflect the shape in
the mirror line shown.
Reflections
Mark position of
vertices, draw image of
shape.
Mirror Line
Reflections
object image
Tracing 2
Reflections
Mirror Line
Reflect the object
shape in the mirror line
shown.object
Reflections
Mirror Line
Reflect the object
shape in the mirror line
shown.object
Mark position of
vertices and draw
image of shape.
Reflections
Mirror Line
Reflect the object
shape in the mirror line
shown.object
Mark position of
vertices and draw
image of shape.
image
What letter
would you get if
you reflected
each shape in its
corresponding
mirror line?
STARTER
What letter
would you get if
you reflected
each shape in its
corresponding
mirror line?
STARTER
What letter would
you get if you
reflected each
shape in its
corresponding
mirror line?
What letter
would you get if
you reflected
each shape in its
corresponding
mirror line?
Shape 1
 Look at this shape.
 Can you spot the vertical reflection of the
shape on the next slide? Hold up the correct
letter when asked.
A B
C D
Congratulations!
The correct answer is B!
Shape 2
 Look at this shape.
 Can you spot the vertical reflection of the
shape on the next slide? Hold up the correct
letter when asked.
A B
C D
Congratulations!
The correct answer is A!
Shape 3
 Look at this shape.
 Can you spot the horizontal reflection of the
shape on the next slide? Hold up the correct
letter when asked.
A B
C D
Congratulations!
The correct answer is D!
Shape 4
 Look at this shape.
 Can you spot the horizontal reflection of the
shape on the next slide? Hold up the correct
letter when asked.
A B
C D
Congratulations!
The correct answer is B!
Shape 5
 Look at this shape.
 Can you spot the diagonal reflection of the
shape on the next slide? Hold up the correct
letter when asked.
A B
C D
Congratulations!
The correct answer is A!
Shape 6
 Look at this shape.
 Can you spot the diagonal reflection of the
shape on the next slide? Hold up the correct
letter when asked.
A B
C D
Congratulations!
The correct answer is D!
Reflections
Vertical lines become Horizontal
Diagonal lines remain Diagonal
Reflections
Horizontal lines become Vertical
Vertical lines become Horizontal
Diagonal lines remain Diagonal
Symmetry greta
Symmetry greta
Symmetry greta
2.
3.
4.
5.
Another kind of symmetry?
What do you think we call this kind of symmetry?
TOP Centre of
rotation
Rotational Symmetry !
We say a shape has ROTATIONAL SYMMETRY if it
fits exactly into itself (looks exactly THE SAME)
when it is rotated.
How many times does this shape fit into itself?
TOP
We say it has rotational symmetry of order 4
A shape may have NO Rotational Symmetry
A shape is said to have
NO Rotational Symmetry
(Rotational Symmetry of
ORDER 1)
If it fits onto itself only
ONE TIME
Equilateral Triangle
An equilateral triangle has rotational symmetry of order ?
12
3
3
Square
A square has rotational symmetry of order ?
Square
Square
A square has rotational symmetry of order ?
Square
A square has rotational symmetry of order ?
12
3
4
4
Regular Pentagon
A regular pentagon has rotational symmetry of order ?
Regular Pentagon
A regular pentagon has rotational symmetry of order ? 5
1
23
4
5
Hexagon
Regular Hexagon
A regular hexagon has rotational symmetry of order ?
Regular Hexagon
A regular hexagon has rotational symmetry of order ?
1
23
4
5 6
Regular Hexagon
A regular hexagon has rotational symmetry of order ? 6
Regular Polygons
What did we say a Regular Polygon is?
A regular polygon is a shape which has:
 All sides equal
 All angles equal
Examples ?
What did we say about lines of symmetry of regular
polygons?
Regular polygons have lines of symmetry equal to the
number of sides/angles that they possess.
What then can we conclude?
Regular polygons have order of rotational
symmetry equal to the number of
sides/angles that they have.
Rectangle
Rectangle
A rectangle has rotational symmetry of order ?
2
1
2
Rectangle
A rectangle has rotational symmetry of order ?
Home Work from FORM 1 Maths Pack
Pg 17 ALL Page (short questions)
Pg 18 No.5 and No.7
TEST & REVISION SESSIONS
Date: Friday 4th April
Topics: Data Handling & Symmetry
Sub-topics :
 Tally Charts
 Bar Charts
 Pie Charts
 Finding the lines of symmetry of a shape
 Drawing the other half of shapes in lines of symmetry
 Finding the Order of Rotation of a shape
Questions 2
Rotational Symmetry
State the order of rotational symmetry for each shape below:
13 14 15 16
17 18 19 20
21 22 23 24
Order 4 Order 1 Order 2 Order 5
Order 2 Order 4 Order 6 Order 3
Order 5 Order 4 Order 3 Order 1
Worksheet 2
Rotational Symmetry
State the order of rotational symmetry for each shape below:
13 14 15 16
17 18 19 20
21 22 23 24

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Symmetry greta

Editor's Notes

  • #51: Ghax l angle li taghmel mal line il line ta lisquare hijja 45 degrees so biex tamel angle ohra ta 45 degrees parigga trid iddur 90 degrees ghalhekk horizontal become vertical and vertical become horizontal
  • #52: Ghax l angle li taghmel mal line il line ta lisquare hijja 45 degrees so biex tamel angle ohra ta 45 degrees parigga trid iddur 90 degrees ghalhekk horizontal become vertical and vertical become horizontal