Symmetry: Lines, Reflection, Rotation
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The document discusses the concept of symmetry, defining line symmetry, and how shapes can be folded to match over themselves. It describes various types of symmetries, including vertical, horizontal, and diagonal lines of symmetry, along with rotational symmetry and its orders for different shapes. Additionally, it includes examples and exercises related to identifying lines of symmetry and calculating rotational symmetry for regular polygons.
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Symmetry: Lines, Reflection, Rotation
- 1. The first three letters of your name • Can you fold the letters in a way that the top half exactly covers the bottom half? • If you can draw a line !
- 2. Symmetry in Letters !
- 3. Symmetry
- 4. What is Symmetry? • If a shape can be folded in half so that one half fits exactly on top of the other, than we say that the shape has got line symmetry. • The fold is called a line of symmetry, it divides the shape into two equal parts! • The lines of symmetry may be vertical, horizontal or diagonal
- 5. 1 LoSOne Line of Symmetry Vertical lines of symmetry Horizontal lines of symmetry Diagonal lines of symmetry
- 6. RectangleThe Rectangle Problem A rectangle has only 2 lines of symmetry and not 4 like the square To see this consider the following: Half a rectangle Mirror Line
- 7. The Rectangle Problem A rectangle has only 2 lines of symmetry and not 4 like the square To see this consider the following: Half a rectangle Mirror Line A reflection in the diagonal would produce a kite!
- 8. Regular Regular Polygons Equilateral Triangle Square Regular Pentagon Regular Hexagon Regular Octagon Regular polygons have lines of symmetry equal to the number of sides/angles that they possess.
- 9. Identify the Lines of Symmetry
- 10. Identify the Lines of Symmetry
- 11. Identify the Lines of Symmetry
- 12. Symmetry in Real Life • God made many things in nature symmetrical! • Humans like to follow God’s footsteps when making objects because in this way things look nicer !
- 13. How many ? • An object may have One line of Symmetry Many lines of Symmetry No lines of Symmetry A circle ? INFINITE LINES OF SYMMETRY !
- 14. Mix 1 How many lines of symmetry for each shape? 4 3 5 8 5
- 15. Formula one Book Pg 49 No. 1 and No.2 Get square mirror again HAPPY WEEKEND!
- 16. Mix 3 2 5 3 2 4 How many lines of symmetry for each shape?
- 17. Mix 4 How many lines of symmetry for each shape? 6 2 4 1 2 1
- 18. Mix 5 How many lines of symmetry for each shape? 1 2 4 5 3
- 19. Tracing 1 Reflections object Mirror Line Reflect the object shape in the mirror line shown.
- 20. object Mirror Line Reflect the shape in the mirror line shown. Reflections Mark position of vertices, draw image of shape.
- 22. Tracing 2 Reflections Mirror Line Reflect the object shape in the mirror line shown.object
- 23. Reflections Mirror Line Reflect the object shape in the mirror line shown.object Mark position of vertices and draw image of shape.
- 24. Reflections Mirror Line Reflect the object shape in the mirror line shown.object Mark position of vertices and draw image of shape. image
- 25. What letter would you get if you reflected each shape in its corresponding mirror line? STARTER
- 26. What letter would you get if you reflected each shape in its corresponding mirror line? STARTER
- 27. What letter would you get if you reflected each shape in its corresponding mirror line?
- 28. What letter would you get if you reflected each shape in its corresponding mirror line?
- 29. Shape 1 • Look at this shape. • Can you spot the vertical reflection of the shape on the next slide? Hold up the correct letter when asked.
- 30. A B C D
- 31. Congratulations! The correct answer is B!
- 32. Shape 2 • Look at this shape. • Can you spot the vertical reflection of the shape on the next slide? Hold up the correct letter when asked.
- 33. A B C D
- 34. Congratulations! The correct answer is A!
- 35. Shape 3 • Look at this shape. • Can you spot the horizontal reflection of the shape on the next slide? Hold up the correct letter when asked.
- 36. A B C D
- 37. Congratulations! The correct answer is D!
- 38. Shape 4 • Look at this shape. • Can you spot the horizontal reflection of the shape on the next slide? Hold up the correct letter when asked.
- 39. A B C D
- 40. Congratulations! The correct answer is B!
- 41. Shape 5 • Look at this shape. • Can you spot the diagonal reflection of the shape on the next slide? Hold up the correct letter when asked.
- 42. A B C D
- 43. Congratulations! The correct answer is A!
- 44. Shape 6 • Look at this shape. • Can you spot the diagonal reflection of the shape on the next slide? Hold up the correct letter when asked.
- 45. A B C D
- 46. Congratulations! The correct answer is D!
- 47. Reflections Vertical lines become Horizontal Diagonal lines remain Diagonal
- 48. Reflections Horizontal lines become Vertical Vertical lines become Horizontal Diagonal lines remain Diagonal
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- 56. Another kind of symmetry? What do you think we call this kind of symmetry? TOP Centre of rotation Rotational Symmetry !
- 57. We say a shape has ROTATIONAL SYMMETRY if it fits exactly into itself (looks exactly THE SAME) when it is rotated. How many times does this shape fit into itself? TOP We say it has rotational symmetry of order 4
- 58. A shape may have NO Rotational Symmetry A shape is said to have NO Rotational Symmetry (Rotational Symmetry of ORDER 1) If it fits onto itself only ONE TIME
- 59. Equilateral Triangle An equilateral triangle has rotational symmetry of order ? 12 3 3
- 60. Square A square has rotational symmetry of order ? Square
- 61. Square A square has rotational symmetry of order ?
- 62. Square A square has rotational symmetry of order ? 12 3 4 4
- 63. Regular Pentagon A regular pentagon has rotational symmetry of order ?
- 64. Regular Pentagon A regular pentagon has rotational symmetry of order ? 5 1 23 4 5
- 65. Hexagon Regular Hexagon A regular hexagon has rotational symmetry of order ?
- 66. Regular Hexagon A regular hexagon has rotational symmetry of order ?
- 67. 1 23 4 5 6 Regular Hexagon A regular hexagon has rotational symmetry of order ? 6
- 68. Regular Polygons What did we say a Regular Polygon is? A regular polygon is a shape which has: • All sides equal • All angles equal Examples ? What did we say about lines of symmetry of regular polygons? Regular polygons have lines of symmetry equal to the number of sides/angles that they possess.
- 69. What then can we conclude? Regular polygons have order of rotational symmetry equal to the number of sides/angles that they have.
- 70. Rectangle Rectangle A rectangle has rotational symmetry of order ?
- 71. 2 1 2 Rectangle A rectangle has rotational symmetry of order ?
- 72. Home Work from FORM 1 Maths Pack Pg 17 ALL Page (short questions) Pg 18 No.5 and No.7
- 73. TEST & REVISION SESSIONS Date: Friday 4th April Topics: Data Handling & Symmetry Sub-topics : • Tally Charts • Bar Charts • Pie Charts • Finding the lines of symmetry of a shape • Drawing the other half of shapes in lines of symmetry • Finding the Order of Rotation of a shape
- 74. Questions 2 Rotational Symmetry State the order of rotational symmetry for each shape below: 13 14 15 16 17 18 19 20 21 22 23 24 Order 4 Order 1 Order 2 Order 5 Order 2 Order 4 Order 6 Order 3 Order 5 Order 4 Order 3 Order 1
- 75. Worksheet 2 Rotational Symmetry State the order of rotational symmetry for each shape below: 13 14 15 16 17 18 19 20 21 22 23 24
Editor's Notes
- #51: Ghax l angle li taghmel mal line il line ta lisquare hijja 45 degrees so biex tamel angle ohra ta 45 degrees parigga trid iddur 90 degrees ghalhekk horizontal become vertical and vertical become horizontal
- #52: Ghax l angle li taghmel mal line il line ta lisquare hijja 45 degrees so biex tamel angle ohra ta 45 degrees parigga trid iddur 90 degrees ghalhekk horizontal become vertical and vertical become horizontal