1. 9.10 rotational symmetry April 10, 2012
Graph the triangle.
A(1,3), B(4, 1), C(3, 2)
Bellwork
Objective: graph rotations and identify rotational symmetry
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2. 9.10 rotational symmetry April 10, 2012
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1. None 6. 10.
2.
11.
3. 7.
4. 12. No, a figure and its reflection are congruent.
D 13.
E
8.
T T'
D' E'
5. 14.
K N N' K'
9.
T U U' T'
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4. 9.10 rotational symmetry April 10, 2012
rotation turns a figure about a fixed point (center of rotation)
angle of rotation angle measure of the rotation
R' Q'
90o R
Center of rotation P Q
A figure and its rotation image are congruent.
All rotations that we will do will be counterclockwise.
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6. 9.10 rotational symmetry April 10, 2012
Find the vertices of the image of ΔACB after a rotation of 180o about the origin.
B
C
A
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7. 9.10 rotational symmetry April 10, 2012
A figure has rotational symmetry if you can rotate it 180o, or less, so that its image matches the original figure.
The angle (or its measure) through which the figure rotates is the angle of rotation.
A
Angle of Rotation is 360o ÷ A'
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8. 9.10 rotational symmetry April 10, 2012
Judging from appearance, state whether the flower has rotational symmetry.
If so, what is the angle of rotation.
2
3 1
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9. 9.10 rotational symmetry April 10, 2012
Does the figure have rotational symmetry? What is the angle of rotation?
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