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# Thursday, January 26th

Thursday, January 26th. Please complete the warm up and write down homework. Warm Up. How do you know if two shapes are similar? S haron bought a shirt for \$42.50 and a pair of jeans for \$52.75. If there’s a 8% sales tax. What will the total be?. Corny Joke of the Day.

## Thursday, January 26th

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### Presentation Transcript

1. Thursday, January 26th Please complete the warm up and write down homework Warm Up How do you know if two shapes are similar? Sharon bought a shirt for \$42.50 and a pair of jeans for \$52.75. If there’s a 8% sales tax. What will the total be?

2. Corny Joke of the Day What type of animal needs oil? Mice because they “squeak”

3. Have you used your holiday present yet? Staple your extra 10 points to any Homework, Quiz, or Classwork assignment Turn it into the math bin 

4. Checkpoint Answers Scored out of 14 GREAT JOB!!!! Remember to watch your decimal placements 

5. Symmetry Preview Write down your definition of symmetry and draw examples that you think represent it!

6. Symmetry

7. Our Mission Learn to identify line symmetry and learn how to rotate figures!

8. What is it? A figure has line symmetry if it can be folded or reflected so that the two parts of the figure match, or are congruent. The line of reflection is called the line of symmetry.

9. Part 1 Lines of symmetry in regular polygons Regular polygons: All side lengths and angles are congruent

10. Can you find the rule? Find the number of lines of symmetry in each shape and fill out the chart.

11. 4 lines of symmetry

12. Discovery For a regular polygon the lines of symmetry is the same as the number of sides!

13. Fun Fact A dodecagon is a 12-sided regular polygon. This means that it has ___________lines of symmetry!

14. Part 2 Determining if the lines given are the lines of symmetry

15. #1 Determine whether each dashed line appears to be a line of symmetry. The two parts of the figure appear to match exactly when folded or reflected across the line. The line appears to be a line of symmetry.

16. #2 Determine whether each dashed line appears to be a line of symmetry. The two parts of the figure do not appear congruent. The line does not appear to be a line of symmetry.

17. #3 Determine whether each dashed line appears to be a line of symmetry. The two parts of the figure do not appear congruent. The line does not appear to be a line of symmetry.

18. #4 Determine whether each dashed line appears to be a line of symmetry. The two parts of the figure appear to match exactly when folded or reflected across the line. The line appears to be a line of symmetry.

19. Group Discussion How many lines of symmetry does the following shape have?

20. NOT EVERY SHAPE HAS A LINE OF SYMMETRY

21. Does this have a line of symmetry?

22. Smile Symmetry Is there a line of symmetry. If so, how many? 1 line of symmetry

23. Corporate Logos Find the symmetry

24. Class Discussion • Situations that demonstrate reflection • Situations that demonstrate rotation?

25. Transformations

26. Cut out the first letter to your name!

27. A rigid transformation moves a figure without changing its size or shape. So the original figure and the transformed figure are always congruent. • The illustrations of the alien will show three transformations: • A rotation • A reflection • A translation • *Notice the transformed alien does not change in size or shape.

28. Type #1 Rotational

29. A rotationis the movement of a figure around a point. A point of rotation can be on or outside a figure. The location and position of a figure can change with a rotation.

30. Example #1 The figure moves around a point. It is a rotation.

31. Example #2 The figure moves around a point. It is a rotation.

32. Rotations are measured by Degrees. • Rotations can turn Clockwise or Counter Clockwise

33. Clockwise “like a clock” Counter-Clockwise “opposite of a clock”

34. A full turn is 360° • ¼ of a turn is • 90° • ½ of a turn is 180° • ¾ of a turn is 270° 360° 90° 180°

35. Just Watch! Draw a 180° rotation about the point shown. Trace the figure and the point of rotation. Place your pencil on the point of rotation. Rotate the figure 180°. Trace the figure in its new location.

36. You Try #1! Draw each transformation. Draw a 180° clockwise rotation about the point shown. Trace the figure and the point of rotation. Place your pencil on the point of rotation. Rotate the figure 180°. Trace the figure in its new location. A A

37. You Try #2! Draw each transformation. Draw a 90° counter clockwise rotation about the point shown. Trace the figure and the point of rotation. Place your pencil on the point of rotation. Rotate the figure 90° Trace the figure in its new location. K K

38. Type #2 Reflection

39. When a figure flips over a line, creating a mirror image, it is called a reflection. The line the figure is flipped over is called line of reflection. The location and position of a figure change with a reflection.

40. There are 2 types! Horizontal: flips ACROSS Vertical: flips UP and DOWN

41. Practice Problems • Reflect Vertically • Reflect horizontally B J

42. Type #3 Translation

43. A translation is the movement of a figure along a straight line. Only the location of the figure changes with a translation.

44. Determine the transformation! Whiteboard Practice

45. The figure is flipped over a line. It is a reflection.

46. The figure is moved along a line. It is a translation.

47. The figure moves around a point. It is a rotation.

48. The figure is flipped over a line. It is a reflection.

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