Warm Up
Find the coordinates of the following
composition transformation of Triangle DOG.
D ( 5, 5)
O ( - 3, 7 )
G (-4, -1 )
Reflect over y = x.
Rotate 90° counterclockwise.
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HW Solutions
Dilations Wksht
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3-5 Symmetry
Objective: Identify types of symmetry in objects.
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A figure has symmetry if there is an isometry that maps the
figure onto itself.
OHIO
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A plane figure has reflectional symmetry or line
symmetry if there is a reflection that maps the
figure onto itself.
If you fold a figure along a line of symmetry,
the halves match exactly.
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A figure has rotational symmetry if there is a rotation
of 180° or less that maps the figure onto itself.
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A rotation of 180° is known as a half-turn.
If a half-turn maps a plane figure onto itself,
the figure has point symmetry.
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What types of symmetry does each figure have?
If it has reflectional, sketch the lines of symmetry.
If it has rotational, state the angle of rotation.
Does it have point symmetry?
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Symmetry in Nature Video
http://www.youtube.com/watch?v=fCKILUeV1xk
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HW # 39
Practice 3-5
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