9.4 ­ Symmetry.notebook
January 09, 2017
9.4: Symmetry
Date: 1/9
A figure with symmetry can be reflected onto itself or rotated
onto itself.
LINE SYMMETRY:
Figures can have one or more than one line of symmetry.
Ex 1). How many lines of symmetry does each shape have?
a) rectangle
b) heart
c) regular octagon
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9.4 ­ Symmetry.notebook
January 09, 2017
ROTATIONAL & POINT SYMMETRY:
If a figure has rotational symmetry, then there is a rotation of
180 or less for which the figure is its own image.
Ex 2). Does the figure have rotational symmetry? If so, what is
the angle of rotation?
a)
b)
c)
d)
e)
f)
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9.4 ­ Symmetry.notebook
January 09, 2017
A figure has point symmetry if an exact 180 rotation maps the
figure onto itself.
Ex 3). Does the figure have point symmetry?
a)
b)
c)
d)
e)
f)
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9.4 ­ Symmetry.notebook
January 09, 2017
THREE DIMENSIONAL SYMMETRY:
A three dimensional object has reflectional symmetry if a
plane divides the object in half.
A three dimensional object has rotational symmetry if when
rotated around a line it will map onto itself.
Ex 4). Does the object have reflectional symmetry in a plane,
rotational symmetry about a line, or both?
a)
b) a cone
c) a basketball
d)
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9.4 ­ Symmetry.notebook
January 09, 2017
Homework:
pg. 599 #1 – 3, 5 – 19, 28 – 31
Quiz ­ Wednesday
MathXL due ­ Wednesday
Exam Review Days ­ Thursday and Friday
Transformation Activity due Friday
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