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Transparency 6

2. Splash Screen

3. Identify symmetry and rotational symmetry
Objective
Identify symmetry and rotational symmetry
Example 6-3b

4. Figures that match exactly when folded in half
Vocabulary
Line symmetry
Figures that match exactly when folded in half
Example 6-3b

5. Vocabulary Line of symmetry
A line that divides a figure into two halves that are reflections of each other
Example 6-3b

6. Vocabulary Rotational symmetry
A figure that can be turned less than 3600 about its center and still look like the original
Example 6-3b

7. The degree measure of the angle through which a figure is rotated
Vocabulary
Angle of rotation
The degree measure of the angle through which a figure is rotated
Example 6-3b

8. Example 1 Identify Line Symmetry
Example 2 Identify Rotational Symmetry
Example 3 Identify Rotational Symmetry
Lesson 6 Contents

9. Left half is reflection of right side
TRILOBITES The trilobite is an animal that lived millions of year ago. Determine whether the figure has line symmetry. If it does, draw all lines of symmetry. If not, write none.
When cut in half
Left half is reflection of right side
Answer: One vertical line of symmetry.
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Example 6-1a

10. One vertical line of symmetry.
BOTANY Determine whether the leaf has line symmetry. If it does, draw all lines of symmetry. If not, write none.
Answer:
One vertical line of symmetry.
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Example 6-1b

11. Rotational Symmetry involves a circle of 3600 4 2
FLOWERS Determine whether the flower design has rotational symmetry. Write yes or no. If yes, name its angle(s) of rotation. 1
All petals look alike
Count number of petals
Rotational Symmetry involves a circle of 3600 4 2
Divide 360 by 4 (number of petals) 90 3
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Example 6-2a

12. Rotate 900 at a time to see the rotational symmetry
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Example 6-2a

13. Answer: Yes, has rotational symmetry. 90, 180, and 270
NOTE: Rotational symmetry will never rotate 3600
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Example 6-2a

14. Answer: yes, rotational symmetry; 180
FLOWERS Determine whether the flower design has rotational symmetry. Write yes or no. If yes, name its angle(s) of rotation.
Answer: yes, rotational symmetry; 180
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Example 6-2b

15. Rotational Symmetry involves a circle of 3600
FLOWERS Determine whether the flower design has rotational symmetry. Write yes or no. If yes, name its angle(s) of rotation. 1
All petals look alike
Count number of petals 6 2
Rotational Symmetry involves a circle of 3600
Divide 360 by 6 (number of petals) 5 3 90 4
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Example 6-3a

16. Answer: Yes, has rotational symmetry. 60°, 120°, 180°, 240°, and 300°.
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Example 6-3a

17. NOTE: Rotational symmetry will never rotate 3600
Answer: Yes, this figure has rotational symmetry. It will match itself after being rotated 60°, 120°, 180°, 240°, and 300°.
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Example 6-3a

18. Answer: no rotational symmetry*
FLOWERS Determine whether the flower design has rotational symmetry. Write yes or no. If yes, name its angle(s) of rotation.
Answer: no rotational symmetry
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Example 6-3b

19. Assignment
Lesson 6:6
Symmetry
All
End of Lesson 6