1. Enlargement Objectives: C GradeEnlarge a shape by a fractional scale factor Compare the area of an enlarged shape with the original shape Find the centre of enlargement B GradeDistinguish between formulae for perimeter, area and volume by considering dimensions A GradeCompare areas and volumes of enlarged shapes Enlarge a shape by a negative scale factor Prior knowledge: Enlarge an object by a positive integer scale factor using a centre of enlargement and ray lines.

2. Enlargement Enlargement is not just for making an object bigger using the scale factor Objects can be enlarged using any number as a scale factor including fractions and negative numbers. object CoE Using a scale factor ½ the distance from the CoE to the image vertices is ½ times the distance from the CoE to the object vertices. Scale Factor ½ Distance from CoE 2 squares right 1 square down 4 squares right 2 squares down x Scale Factor ½ Distance from CoE 5 squares right 1 square down 10 squares right 2 squares down x Scale Factor ½ Distance from CoE 2 squares right 3 squares down 4 squares right 6 squares down x This gives us enough information to draw the image

3. Enlargement Negative scale factors can also be used - 8 - 7 - 6 - 5 -4 - 3 - 2 - 1 0 1 2 3 4 5 6 7 8 9 5 4 3 2 1 - 1 - 2 - 3 - 4 - 5 CoE A negative scale factor takes the image the opposite side of the centre of enlargement Enlarge the object by a scale factor of - 2

4. Enlargement - 8 - 7 - 6 - 5 -4 - 3 - 2 - 1 0 1 2 3 4 5 6 7 8 9 5 4 3 2 1 - 1 - 2 - 3 - 4 - 5 CoE Enlarge the object by a scale factor of - 3 Notice how the image is upside down from the object

5. Enlargement In each case object A has been enlarged to image B Find the scale factor and centre of enlargement for A A B B A B A B Scale Factor ½ Scale Factor - 1

6. Enlargement In each case object A has been enlarged to image B Find the scale factor and centre of enlargement for A A B B A B A B Worksheet 3