Symmetry:Symmetry:A Visual PresentationA Visual Presentation

Line SymmetryLine Symmetry Shape has line symmetry when one Shape has line symmetry when one

halfhalfof it is the mirror image of the other of it is the mirror image of the other half.half.

Symmetry can have vertical, horizontal Symmetry can have vertical, horizontal or diagonal line symmetry.or diagonal line symmetry.

Is a butterfly Is a butterfly symmetrical?symmetrical?

Line Symmetry exists in Line Symmetry exists in nature but you may not nature but you may not

have noticed.have noticed.

At the  beach there are At the  beach there are a variety of shells with a variety of shells with vertical line symmetry.vertical line symmetry.

Under the sea there are also Under the sea there are also many symmetrical objects such many symmetrical objects such as these crabs. They have as these crabs. They have horizontal symmetry.horizontal symmetry.

This starfish has vertical and This starfish has vertical and diagonal symmetry.diagonal symmetry.

Animals that have Line Animals that have Line SymmetrySymmetry

Here are a few more great examples of Here are a few more great examples of vertical symmetry in the animal vertical symmetry in the animal

kingdom.kingdom.

THESE MASKS HAVE THESE MASKS HAVE SYMMETRYSYMMETRY

These masks have a line of These masks have a line of symmetry from the forehead to the symmetry from the forehead to the

chin.chin.    

The human face also has a line of The human face also has a line of symmetry in the same place.symmetry in the same place.

REFLECTION IN WATERREFLECTION IN WATER

If an object is If an object is reflected in water it reflected in water it

is considered to is considered to have line have line

symmetry along symmetry along the waterline. This the waterline. This is called horizontal is called horizontal

symmetry.symmetry.

The Taj MahalThe Taj Mahal

Symmetry exists in architecture all Symmetry exists in architecture all around the world.  The best known around the world.  The best known example of this is the Taj Mahal.example of this is the Taj Mahal.

This photograph shows 2 lines of symmetry. One This photograph shows 2 lines of symmetry. One vertical, the other horizontal along the vertical, the other horizontal along the

waterline.waterline.

(Notice how the prayer towers, called minarets, are reflected in the water (Notice how the prayer towers, called minarets, are reflected in the water and side to side).and side to side).

2D Shapes and 2D Shapes and SymmetrySymmetry

LetLet’’s look at 2D shapes s look at 2D shapes to find lines of to find lines of

symmetry. symmetry.    

How many lines of How many lines of symmetry did you symmetry did you

find for each shape?find for each shape?

An equilateral triangle has 3 lines of An equilateral triangle has 3 lines of symmetry. symmetry. 

        A square has 4 lines of symmetry.  A square has 4 lines of symmetry. 

   

    A regular pentagon has 5 lines of A regular pentagon has 5 lines of symmetry.symmetry.

  

A regular hexagon has 6 lines of A regular hexagon has 6 lines of symmetry . symmetry .

        A regular octagon has 8 lines of A regular octagon has 8 lines of

symmetry.symmetry.

LetLet’’s do a practice problem together:s do a practice problem together:

Lisa and Rob are flying a rhombus shaped Lisa and Rob are flying a rhombus shaped kite. They need to fold the kite in half kite. They need to fold the kite in half along a line of symmetry to have it fit in a along a line of symmetry to have it fit in a backpack. Which picture shows the lines backpack. Which picture shows the lines they can choose from? they can choose from?

A B C DA B C D

D