1. Warm Up 1. Give the coordinates of triangle ABC with vertices (7, 2), (1, 2), (4, –5) reflected across the y-axis. 2. Give the coordinates of triangle ABC translated 3 units left and 2 units down. Course 2 7-11 Symmetry

2. Learn to identify symmetry in figures. Course 2 7-11 Symmetry

3. Vocabulary line symmetry line of symmetry asymmetry rotational symmetry center of rotation Insert Lesson Title Here Course 2 7-11 Symmetry

4. When you can draw a line through a plane figure so that the two halves are mirror images of each other, the figure has line symmetry, or is symmetrical. The line along which the figure is divided is called the line of symmetry. When a figure is not symmetrical then it has asymmetry, or is asymmetrical Course 2 7-11 Symmetry

5. Decide whether each of the figures has line symmetry. If it does, draw all the lines of symmetry. Additional Example 1: Identifying Line Symmetry A.B. no line of symmetry 1 line of symmetry Course 2 7-11 Symmetry

6. Try This: Example 1A & 1B Decide whether each figure has line symmetry. If it does, draw all lines of symmetry. Insert Lesson Title Here A.B. 1 line of symmetryno line of symmetry Course 2 7-11 Symmetry

7. Find all the lines of symmetry in each figure. Additional Example 2A & 2B: Finding Lines of Symmetry A. There are two lines of symmetry. B. There are no lines of symmetry. Course 2 7-11 Symmetry

8. Try This: Example 2A & 2B Insert Lesson Title Here Find all the lines of symmetry in each figure. B. There is 1 line of symmetry. A. There are no lines of symmetry. Course 2 7-11 Symmetry

9. A figure has rotational symmetry if, when it is rotated less than 360° around a central point, it coincides with itself. The central point is called the center of rotation. Course 2 7-11 Symmetry

10. Additional Example 3A: Identifying Rotational Symmetry Tell how many times each figure will show rotational symmetry within one full rotation. A. Draw lines from the center of the figure out through identical places in the figure. Count the number of lines drawn. The figure will show rotational symmetry 5 times within a 360° rotation. Course 2 7-11 Symmetry

11. Tell how many times each figure will show rotational symmetry with one full rotation. Additional Example 3B: Identifying Rotational Symmetry Draw lines from the center of the figure out through identical places in the figure. Count the number of lines drawn. The figure will show rotational symmetry 4 times within a 360° rotation. B. Course 2 7-11 Symmetry

12. Try This: Example 3A Tell how many times each figure will show rotational symmetry within one full rotation. Insert Lesson Title Here A. Draw lines from the center of the figure out through identical places in the figure. Count the number of lines drawn. The figure will show rotational symmetry 4 times within a 360° rotation. Course 2 7-11 Symmetry

13. Try This: Example 3B Insert Lesson Title Here Tell how many times each figure will show rotational symmetry within one full rotation. B. Draw lines from the center of the figure out through identical places in the figure. Count the number of lines drawn. The figure will show rotational symmetry 4 times within a 360° rotation. Course 2 7-11 Symmetry

14. Lesson Quiz Does the figure described have symmetry? Insert Lesson Title Here 1. a regular hexagon with a line drawn through the middle and two vertices 2. a square with a diagonal line drawn in 3. a heart with a horizontal line drawn through the middle 4. Tell how many times the figure will have rotational symmetry with one full rotation. yes no 6 Course 2 7-11 Symmetry

15. Assignment Page 398 – 399 –# 1 – 23, 27 - 34