1. Splash Screen

2. Five-Minute Check (over Lesson 9–4) Then/Now New Vocabulary
Key Concept: Line Symmetry
Example 1: Real-World Example: Identify Line Symmetry
Key Concept: Rotational Symmetry
Example 2: Identify Rotational Symmetry
Key Concept: Three-Dimensional Symmetries
Example 3: Three-Dimensional Symmetry
Lesson Menu

3. Triangle XYZ has vertices X(–3, 1), Y(–4, 5), and Z(0, 5)
Triangle XYZ has vertices X(–3, 1), Y(–4, 5), and Z(0, 5). Graph ΔXYZ and its image after the indicated glide reflection. Translation: along 5, –2, Reflection: in x-axis
A. B.
C. D.
5-Minute Check 1

4. Triangle XYZ has vertices X(–3, 1), Y(–4, 5), and Z(0, 5)
Triangle XYZ has vertices X(–3, 1), Y(–4, 5), and Z(0, 5). Graph ΔXYZ and its image after the indicated glide reflection. Translation: along 0, –4, Reflection: in y-axis
A. B.
C. D.
5-Minute Check 2

5. Which of the following characteristics is not preserved under a glide reflection?
A. length
B. angle measure
C. orientation
D. parallel lines
5-Minute Check 3

6. You drew reflections and rotations of figures. (Lessons 9–1 and 9–3)
Identify line and rotational symmetries in two-dimensional figures.
Identify line and rotational symmetries in three-dimensional figures.
Then/Now

7. symmetry line symmetry line of symmetry rotational symmetry
center of symmetry
order of symmetry
magnitude of symmetry
plane symmetry
axis symmetry
Vocabulary

8. Concept

9. Answer: yes; 7 lines of symmetry
Identify Line Symmetry
A. KALEIDOSCOPES State whether the object appears to have line symmetry. Write yes or no. If so, draw all lines of symmetry, and state their number.
Answer: yes; 7 lines of symmetry
Example 1

10. Identify Line Symmetry
B. KALEIDOSCOPES State whether the object appears to have line symmetry. Write yes or no. If so, draw all lines of symmetry, and state their number.
Answer: no
Example 1

11. Answer: yes; 5 lines of symmetry
Identify Line Symmetry
C. KALEIDOSCOPES State whether the object appears to have line symmetry. Write yes or no. If so, draw all lines of symmetry, and state their number.
Answer: yes; 5 lines of symmetry
Example 1

12. A. State whether the figure appears to have line symmetry
A. State whether the figure appears to have line symmetry. Write yes or no. If so, state their number.
A. yes; 1 line
B. yes; 2 lines
C. yes; 3 lines
D. no
Example 1

13. B. State whether the figure appears to have line symmetry
B. State whether the figure appears to have line symmetry. Write yes or no. If so, state their number.
A. yes; 1 line
B. yes; 2 lines
C. yes; 4 lines
D. no
Example 1

14. C. State whether the figure appears to have line symmetry
C. State whether the figure appears to have line symmetry. Write yes or no. If so, state their number.
A. yes; 1 line
B. yes; 2 lines
C. yes; 4 lines
D. no
Example 1

15. Concept

16. Identify Rotational Symmetry
A. State whether the figure has rotational symmetry. Write yes or no. If so, locate the center of symmetry, and state the order and magnitude of symmetry.
Answer: Yes the star has order 5 rotatonal symmetry and magnitude 360 ÷ 5 = 72°. The center of the star is the center of rotation.
Example 2

17. Identify Rotational Symmetry
B. State whether the figure has rotational symmetry. Write yes or no. If so, locate the center of symmetry, and state the order and magnitude of symmetry.
Answer: The propeller has order 3 rotational symmetry and magnitude 360 ÷ 3 = 120°. The center of the propeller is the center of rotation.
Example 2

18. Identify Rotational Symmetry
C. State whether the figure has rotational symmetry. Write yes or no. If so, locate the center of symmetry, and state the order and magnitude of symmetry.
Answer: The gear has order 8 rotational symmetry and magnitude 360 ÷ 8 = 45°. The center of the gear is the center of rotation.
Example 2

19. A. Yes, order 8 and magnitude 45° B. Yes, order 4 and magnitude 90°
A. State whether the figure has rotational symmetry. If so, state the order and magnitude of symmetry.
A. Yes, order 8 and magnitude 45°
B. Yes, order 4 and magnitude 90°
C. Yes, order 4 and magnitude 180°
D. No, the figure does not have rotational symmetry.
Example 2

20. A. Yes, order 8 and magnitude 45° B. Yes, order 6 and magnitude 60°
B. State whether the figure has rotational symmetry. If so, state the order and magnitude of symmetry.
A. Yes, order 8 and magnitude 45°
B. Yes, order 6 and magnitude 60°
C. Yes, order 4 and magnitude 90°
D. No, the figure does not have rotational symmetry.
Example 2

21. A. Yes, order 3 and magnitude 90° B. Yes, order 4 and magnitude 90°
C. State whether the figure has rotational symmetry. If so, state the order and magnitude of symmetry.
A. Yes, order 3 and magnitude 90°
B. Yes, order 4 and magnitude 90°
C. Yes, order 2 and magnitude 180°
D. No, the figure does not have rotational symmetry.
Example 2

22. Concept

23. Answer: both plane and axis symmetry
Three-Dimensional Symmetry
A. State whether the figure has plane symmetry, axis symmetry, both, or neither.
Answer: both plane and axis symmetry
Example 3

24. Answer: neither plane nor axis symmetry
Three-Dimensional Symmetry
B. State whether the figure has plane symmetry, axis symmetry, both, or neither.
Answer: neither plane nor axis symmetry
Example 3

25. A. State whether the figure has plane symmetry, axis symmetry, both or neither.
A. plane symmetry
B. axis symmetry
C. both
D. neither
Example 3

26. B. State whether the figure has plane symmetry, axis symmetry, both or neither.
A. plane symmetry
B. axis symmetry
C. both
D. neither
Example 3

27. End of the Lesson