9.10 notes

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Page 1: 9.10 notes

9.10 rotational symmetry

HW pg. 509 #1­17 odds 1

April 10, 2012

Objective: graph rotations and identify rotational symmetry

Graph the triangle.A(1,3), B(4, 1), C(3, ­2)

Bellwork

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 2

April 10, 2012

page 505 # 1­ 1. None2. 

3. 

4.  12. No, a figure and its reflection are congruent.13. 

14. 

 6. 

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8. 

9. 

D ET T'

E'D'

K N

T U

N' K'

T'U'

5.

10.  

11. 

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 3

April 10, 2012

15.

16.

17.

18.

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 4

April 10, 2012

rotation ­ turns a figure about a fixed point (center of rotation)

angle of rotation ­ angle measure of the rotation

90o

P Q

R

R' Q'

Center of rotation

A figure and its rotation image are congruent.

All rotations that we will do will be counterclockwise.

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 5

April 10, 2012

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 6

April 10, 2012

Find the vertices of the image of ΔACB after a rotation of 180o about the origin.

A

BC

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 7

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

A'Angle of Rotation is 360o ÷ 

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 8

April 10, 2012

Judging from appearance, state whether the flower has rotational symmetry.  If so, what is the angle of rotation.

1

2

3

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 9

April 10, 2012

Does the figure have rotational symmetry?  What is the angle of rotation?

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9.10 rotational symmetry

HW pg. 509 #1­17 odds 10

April 10, 2012

9.10 HW pg. 509 #1 ­ 17 odds