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2.
Enlarge this rectangle by a scale factor of 2 about the marked centre of enlargement C
Centre of
Enlargement
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3. 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
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4. 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
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5. 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 C
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6. Why is the centre of enlargement important?
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7. Why is the centre of enlargement important?
Can you see where the rest of the shape will be? C
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8. Why is the centre of enlargement important?
Can you see where the rest of the shape will be? C
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9. Why is the centre of enlargement important?
Can you see where the rest of the shape will be? C
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10. Why is the centre of enlargement important?
To enlarge a shape you need:
A Scale Factor
Centre of Enlargement C
(Size)
(Position) I
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11.
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
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12. Enlarge this shape by a scale factor of 3 about the marked centre of enlargement C
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13. Enlarge this shape by a scale factor of 3 about the marked centre of enlargement
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14. Enlarge this shape by a scale factor of 3 about the marked centre of enlargement
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15. Enlarge this shape by a scale factor of 3 about the marked centre of enlargement
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16. The Different Positions
of the
Centre of Enlargement
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17. The centre of enlargement can lie on a corner of the shape
x 4
x 3
x 2 C
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18. The centre of enlargement can lie on a side of the shape
x 3
x 2 C
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19. The centre of enlargement can lie inside the shape
x 3
x 2 C
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20. Formal Enlargement on square paper
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21. If you are using square paper you can use the following method to enlarge:
Scale factor 3 C
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22. If you are using square paper you can use the following method to enlarge:
Scale factor 3 2 4
x 3 C 6 12
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23. Finding The Centre of Enlargement
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24. Where is the centre of enlargement?
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25. Where is the centre of enlargement?
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26. Scale Factor Pairs
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27. x 2 x ½ B A C What is the scale factor from A to B?
What is the scale factor from B to A? C B A
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28. x 3 B x A C What is the scale factor from A to B?
What is the scale factor from B to A? B x 1 3 A C
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29. What is the scale factor from A to B?x 3 2
What is the scale factor from B to A? x 2 3 C A B
The scale factors which transform object to image and vice versa are always reciprocals of each other
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30. Negative Scale Factors
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31. What is the meaning of a negative scale factor?
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32. -ve +ve A B C What is the scale factor from B to A?
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?
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33. Enlarge object A by a scale factor of -1
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
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34. Enlarge object A by a scale factor of -1-2 C A B
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35. A B – C What is the scale factor from B to A?
Enlarge object A by a scale factor of -1 -2 C A B – 1 2
What is the scale factor from B to A?
What combination of transformations would have produced the same result from A to B?
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37. Enlarge the triangle shown below by a scale factor of 3, with centre of enlargement the origin.9 8 7 6 5 4 3 2 1 -1 -2 -3 -4
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39. Enlarge the triangle shown below by a scale factor of 2½, with centre of enlargement the point P.9 8 7 6 5 4 3 2 1 -1 -2 -3 -4 -5 -6 -7 P
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41. Enlarge the trapezium shown below by a scale factor of ½, with centre of enlargement the origin.10 8 6 4 2 -2 -4 -6 -8 5 1 3 7 9 11 12 13 14 15 -5
-10 -1 -3 -7 -9
-11
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43. R Q P Shape P is enlarged to give shape Q.
One side of shape Q is drawn for you.
What is the scale factor for this enlargement?
Complete shape Q.
What are the co ordinates of the centre of enlargement?
Enlarge shape P by a scale factor of ½ about (3,14) to give shape R. 16 14 12 10 8 6 4 2 5 15 13 11 9 7 3 1 18 17 19
the scale factor from P to Q is 2 R Q
the centre of enlargement is at
(0,0) P
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44. 5 4 3 2 1 -1 -2 -3 -4 -5
Exam Question
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45. P Enlarge this triangle by a scale factor of 1½, about P 5 4 3 2 1 -1 5 4 3 2 1 -1 -2 -3 -4 -5
Enlarge this triangle by a scale factor of 1½, about P P
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47. Q P Shape P is enlarged to give shape Q.
One of the sides of shape Q has been drawn on the grid.
State the scale factor for this enlargement.
Complete shape Q on the grid. A B A B Q P C D C D E
The scale factor is E
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