1. 7-8 Symmetry Course 3 Warm Up Warm Up Problem of the Day Problem of the Day Lesson Presentation Lesson Presentation

2. Warm Up 1.  3602.  360 3.  3604.  360 5.  360 Course 3 7-8 Symmetry 1212 1414 1818 3535 2323 90 180 45 216 240

3. Problem of the Day Name four plane figures that can be rotated 180° around a center point and look the same after the rotation as they did before. Course 3 7-8 Symmetry Possible answer: rectangle, square, parallelogram, regular hexagon.

4. Learn to identify symmetry in figures. Course 3 7-8 Symmetry

5. Course 3 7-8 Symmetry line symmetry line of symmetry rotational symmetry Vocabulary

6. Course 3 7-8 Symmetry Nature provides beautiful examples of symmetry, such as the wings of a butterfly or petals of a flower. Symmetric objects have parts that are congruent. A figure has line symmetry if you can draw a line through it so the the two sides are mirror images of each other. The line is called line of symmetry.

7. Course 3 7-8 Symmetry If you fold a figure on the line of symmetry, the halves match exactly. Helpful Hint

8. Course 3 7-8 Symmetry Additional Example 1A: Drawing Figures With Line Symmetry Complete the figure. The dashed line is the line of symmetry.

9. Course 3 7-8 Symmetry Additional Example 1B: Drawing Figures With Line Symmetry Continued Complete the figure. The dashed line is the line of symmetry.

10. Course 3 7-8 Symmetry Check It Out: Example 1A Complete the figure. The dashed line is the line of symmetry.

11. Course 3 7-8 Symmetry Complete the figure. The dashed line is the line of symmetry. Check It Out: Example 1B

12. Course 3 7-8 Symmetry A figure has rotational symmetry if you can rotate the figure around some point so that it coincides with itself. The point is the center of rotation, and the amount of rotation must be less than one full turn or 360°. 6-fold rotational symmetry 8-fold rotational symmetry 6-fold and 8-fold rotational symmetry mean that the figures coincide with themselves 6 times and 8 times respectively, within one full turn.

13. Course 3 7-8 Symmetry Additional Example 2A: Drawing Figures With Rotational Symmetry 2-fold Complete the figure. The point is the center of rotation. The figure coincides with itself every 180°

14. Course 3 7-8 Symmetry Additional Example 2B: Drawing Figures With Rotational Symmetry Continued 5-fold Complete the figure. The point is the center of rotation. The figure coincides with itself every 72°

15. Course 3 7-8 Symmetry Check It Out: Example 2A 8-fold Complete the figure. The point is the center of rotation. The figure coincides with itself every 45°

16. Course 3 7-8 Symmetry 10-fold The figure coincides with itself every 36° Check It Out: Example 2B Complete the figure. The point is the center of rotation.

17. Course 3 7-8 Symmetry Lesson Quiz: Part I Does the figure described have symmetry? 1. a regular hexagon 2. the letter F 3. the letter M yes no yes

18. Course 3 7-8 Symmetry Lesson Quiz: Part II 4. Complete the figure. The dashed line is the line of symmetry.