Symmetry: A Visual Presentation Line Symmetry Shape has lin

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SymmetryA Visual Presentation
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Line Symmetry

• Shape has line symmetry when one halfof it is
  the mirror image of the other half.
• Symmetry can have vertical, horizontal or
  diagonal line symmetry.

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Is a butterfly symmetrical?
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Line Symmetry exists in nature but you may not
have noticed.
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At the  beach there are a variety of shells with
vertical line symmetry.
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Under the sea there are also many symmetrical
objects such as these crabs. They have
horizontal symmetry. This starfish has
vertical and diagonal symmetry.
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Animals that have Line Symmetry

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

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THESE MASKS HAVE SYMMETRY

• These masks have a line of symmetry from the
  forehead to the chin.  
• The human face also has a line of symmetry in the
  same place.

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REFLECTION IN WATER

• If an object is reflected in water it is
  considered to have line symmetry along the
  waterline. This is called horizontal symmetry.

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The Taj Mahal

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

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• This photograph shows 2 lines of symmetry. One
  vertical, the other horizontal along the
  waterline.
• (Notice how the prayer towers, called minarets,
  are reflected in the water and side to side).

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2D Shapes and Symmetry

• Lets look at 2D shapes to find lines of
  symmetry.  

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• How many lines of symmetry did you find for each
  shape?

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• An equilateral triangle has 3 lines of symmetry. 

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•     A square has 4 lines of symmetry.   

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•   A regular pentagon has 5 lines of symmetry. 

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• A regular hexagon has 6 lines of symmetry .

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•     A regular octagon has 8 lines of symmetry.

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Lets do a practice problem together

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

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D