#### Transcript Symmetry (Planes of)

```One Line of Symmetry
Vertical lines
of symmetry
Horizontal lines
of symmetry
Diagonal lines of
symmetry
1 LoS
2 Lines of Symmetry
2 LoS
The Rectangle Problem
Rectangle
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:
A reflection in the diagonal
would produce a kite!
Half a rectangle
Mirror Line
3 LoS
3 Lines of Symmetry
4 LoS
4 Lines of Symmetry
5 Lines of Symmetry
5 LoS
6 LoS
6 Lines of Symmetry
Regular Polygons
Equilateral Triangle
Square
Regular Pentagon
Regular polygons
have lines of
symmetry equal to
the number of
sides/angles that
they possess.
Regular Hexagon
Regular Octagon
Regular
How many lines of symmetry for each shape?
4
3
6
Mix 1
5
8
How many lines of symmetry for each shape?
6
5
3
Mix 2
4
5
How many lines of symmetry for each shape?
2
2
5
3
Mix 3
4
How many lines of symmetry for each shape?
Mix 4
6
2
1
2
4
1
How many lines of symmetry for each shape?
1
2
4
Mix 5
5
3
How many lines of symmetry for each shape?
8
4
6
1
1
Mix 6
Plane Symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A Cuboid
A Cuboid has 3 planes of symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A Cuboid
A Cuboid has 3 planes of symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A Cuboid
A Cuboid has 3 planes of symmetry
Cuboid
3 Planes of
symmetry
Can you explain why the plane shown is not a plane of symmetry?
This is similar to the situation for
the rectangle which does not have
a line of symmetry through its
diagonal. Reflection through the
diagonal produces a kite.
No Diagonal
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A square based prism
A square based prism has 5 Planes of symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A square based prism
A square based prism has 5 Planes of symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A square based prism
A square based prism has 5 Planes of symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A square based prism
A square based prism has 5 Planes of symmetry
Plane Symmetry
A plane of symmetry divides a three dimensional shape into two congruent
halves that are mirror images of each other.
A square based prism
A square based prism has 5 Planes of symmetry
Square
based
prism
5 Planes
of
symmetry
The 9 Plane Symmetries of the Cube
Cube
Triangular Based Prisms
An isosceles triangular based prism has 2 planes of symmetry.
Triangular
Isos
Triangular Based Prisms
An isosceles triangular based prism has 2 planes of symmetry.
Triangular Based Prisms
An isosceles triangular based prism has 2 planes of symmetry.
Triangular Based Prisms
An equilateral triangular based prism has four planes of symmetry.
Triangular Equilateral
Triangular Based Prisms
An equilateral triangular based prism has four planes of symmetry.
Triangular Based Prisms
An equilateral triangular based prism has four planes of symmetry.
Triangular Based Prisms
An equilateral triangular based prism has four planes of symmetry.
Triangular Based Prisms
An equilateral triangular based prism has four planes of symmetry.
Pyramids
A rectangular based pyramid has 2 planes of symmetry.
Pyramids
Pyramids
A square based pyramid has 4 planes of symmetry.
Pyramids
Regular Tetrahedron: 6 planes of symmetry
State the number of planes of symmetry for each shape
1
Questions2
6
4
3
2
1
5
Infinite
6
1
5
8
7
4
9
3
2
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