1. Identify line and rotational symmetries in 2 & 3-dimensioanl figures.
Geometry
Lesson: 9 – 5
Symmetry
Objective:
Identify line and rotational symmetries in 2 & 3-dimensioanl figures.

2. Symmetry
A figure is symmetric if a rigid motion – reflection, translation, rotation, or glide reflection – maps the figure onto itself.
Line symmetry

3. State whether the object appears to have line symmetry. Write yes or no. If so, draw all lines of symmetry, and state their number.
1 line of symmetry

4. State whether the object appears to have line symmetry. Write yes or no. If so, draw all lines of symmetry, and state their number.
5 lines of symmetry

5. No lines of symmetry It’s an oyster…
State whether the object appears to have line symmetry. Write yes or no. If so, draw all lines of symmetry, and state their number.
It’s an oyster…
No lines of symmetry

6. Rotational Symmetry

7. Magnitude of symmetry (or angle of rotation)
Order of symmetry
The number of times a figure maps onto itself.
Magnitude of symmetry (or angle of rotation)
The smallest angle through which a figure can be rotated so that it maps
Magnitude = 360 / order

8. Can turn it 6 times to lay back on itself.
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.
Can turn it 6
times to lay
back on itself.

9. No rotational symmetry.
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.
No rotational symmetry.

10. Can turn it 2 times to lay back on itself.
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.
Can turn it 2
times to lay
back on itself.

11. Can turn it 5 times to lay back on itself.
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.
Can turn it 5
times to lay
back on itself.

12. Can turn it 3 times to lay back on itself.
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.
Can turn it 3
times to lay
back on itself.

13. Can turn it 8 times to lay back on itself.
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.
Can turn it 8
times to lay
back on itself.

14. Plane symmetry
Has also plane symmetry

15. State whether the figure has plane symmetry, axis symmetry, both, or neither.

16. Both Neither Plane Both
State whether each piece of sports equipment appears to have symmetry, axis symmetry, both, or neither (ignore stitching or markings).
Both
Neither
Plane
Both

17. Draw dilations in the coordinate plane.
Geometry
Lesson: 9 – 6
Dilation
Objective:
Draw dilations in the coordinate plane.

18. Draw a dilation Use the book’s example
Will be extra credit if accurate.

19. Dilation Enlargement Reduction
Dilation is bigger than original figure.
Scale factor is bigger than 1
Reduction
Dilation is smaller than original figure.
Scale factor is smaller than 1

20. Dilations in the coordinate plane

22. Homework
Worksheet Pg. 32 & 33
Worksheet Pg. 38 & 39