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# Reflection

Reflection. Reflection. To reflect harder shapes, we reflect each of their corners separately and then join the reflected points. I. O. Reflection produces congruent shapes. To reflect harder shapes, we reflect each of their corners separately and then join the reflected points. O. I.

## Reflection

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### Presentation Transcript

1. Reflection Reflection

2. To reflect harder shapes, we reflect each of their corners separately and then join the reflected points I O Reflection produces congruent shapes

3. To reflect harder shapes, we reflect each of their corners separately and then join the reflected points O I

4. Rotation

5. What is the meaning of Rotation? • Rotate the rectangle: • 90° • Clockwise • About C O c Centre of Rotation I Rotation is a Transformation

6. What is the meaning of Rotation? • Rotate the triangle: • 90° • Anti-clockwise • About C O I c Rotation produces congruent shapes

7. Formal Rotation

8. How do we rotate a shape in general? • Rotate this shape: • 60° • Anti-clockwise • About C O I 60° c

9. How do we rotate a shape in general? • Rotate this shape: • 60° • Anti-clockwise • About C O I 60° c

10. Sliding Translation = Horizontal Steps vector Vertical Steps I O

11. 01234567891011121314151617181920212223 Enlarge this rectangle by a scale factor of 2 about the marked centre of enlargement C Centre of Enlargement

12. 01234567891011121314151617181920212223 Enlarge this rectangle by a scale factor of 2 about the marked centre of enlargement Can you see where the rest of the shape will be? C

13. 01234567891011121314151617181920212223 Enlarge this rectangle by a scale factor of 2 about the marked centre of enlargement Can you see where the rest of the shape will be? C

14. 01234567891011121314151617181920212223 Enlarge this rectangle by a scale factor of 2 about the marked centre of enlargement Can you see where the rest of the shape will be? I 0 C

15. 01234567891011121314151617181920212223 Enlarge this shape by a scale factor of 3 about the marked centre of enlargement Can you see where the rest of the shape will be? C

16. 01234567891011121314151617181920212223 Enlarge this shape by a scale factor of 3 about the marked centre of enlargement C

17. 01234567891011121314151617181920212223 Enlarge this shape by a scale factor of 3 about the marked centre of enlargement C

18. 01234567891011121314151617181920212223 Enlarge this shape by a scale factor of 3 about the marked centre of enlargement C

19. Enlarge this shape by a scale factor of 3 about the marked centre of enlargement I C O

20. The Different Positions of the Centre of Enlargement

21. Finding The Centre of Enlargement

22. Scale Factor Pairs

23. x 2 What is the scale factor from A to B? x ½ What is the scale factor from B to A? B C A

24. x 1 3 What is the scale factor from A to B? x 3 What is the scale factor from B to A? B A C

25. x x 2 3 3 2 What is the scale factor from A to B? What is the scale factor from B to A? C A B The scale factors which transform object to image and vice versa are always reciprocals of each other

26. Negative Scale Factors

27. What is the meaning of a negative scale factor?

28. Enlarge object A by a scale factor of -1 +ve -ve C A B What is the scale factor from B to A? What other single transformation would have produced the same result from A to B?

29. Enlarge object A by a scale factor of -1 C A B The Enlargement with scale factor -1 and a given centre of enlargement C is the same as a rotation by 180° about C , and C is also known as centre of symmetry

30. 1 2 Enlarge object A by a scale factor of -1 -2 C A B What is the scale factor from B to A? What combination of transformations would have produced the same result from A to B?

31. Summary on Transformations

32. REFLECTION • Object • Line of reflection • Congruent Image • Orientation is not maintained ROTATION • Object • Centre of Rotation • Direction of Rotation • Amount of Rotation • Congruent Image • Orientation is not maintained TRANSLATION • Object • Vector • Congruent Image • Orientation is maintained ENLARGEMENT • Object • Scale Factor • Centre of Enlargement • Similar Image • Orientation is maintained or • turned “upside down”

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