## Presentation on theme: "© Boardworks Ltd 2001 Menu Penair School Enlargements 1."— Presentation transcript:

© Boardworks Ltd 2001 Menu Penair School ENLARGEMENTS B. DRAWING ENLARGEMENTS A. SCALE FACTORS C. CENTRES OF ENLARGEMENT D. OTHER SCALE FACTORS

© Boardworks Ltd 2001 Menu Penair School Enlargements Odd One Out A1 A2 A3 A4 A5 A6 Guess the scale factor B1 B2 B3 Practice exercises exploring the idea of scale factor. Some of the numbers involved are deliberately tricky in order to generate discussion and “hands on” measurement of corresponding lengths. DRAWING ENLARGMENTS: This section demonstrates how enlargements are drawn from a given center of enlargement and a scale factor. General Examples C1 C2 C3 C4 C5 Examples on Grids A number of practice exercises where the idea of “scale factor“ is explored. F1 F2 F3 E1 E2E3 Fractional Enlargements Negative Enlargements FINDING THE CENTRE OF ENLARGEMENT: How lines are drawn back through corresponding points to give the centre of enlargement. D1D2D3D4D5 Example 5 Spelt out!

© Boardworks Ltd 2001 Menu Penair School SECTION A A. BASICS + SCALE FACTORS x 2 ?

© Boardworks Ltd 2001 Menu Penair School Odd One Out? In each of the diagrams TWO have been enlarged by the SAME scale factor. Look carefully at the lengths on the diagrams and.... Spot the ODD ONE OUT?

© Boardworks Ltd 2001 Menu Penair School A B C Odd One Out? A1

© Boardworks Ltd 2001 Menu Penair School A x 2 B C x 3 Odd One Out? A1

© Boardworks Ltd 2001 Menu Penair School A B C Odd One Out? A2

© Boardworks Ltd 2001 Menu Penair School A x 2 B C x 3 Odd One Out? A2

© Boardworks Ltd 2001 Menu Penair School A B C Odd One Out? A3

© Boardworks Ltd 2001 Menu Penair School A x 1.5 B C x 2 Odd One Out? A3

© Boardworks Ltd 2001 Menu Penair School A B C Odd One Out? A4

© Boardworks Ltd 2001 Menu Penair School A x 3 B C x 2 Odd One Out? A4

© Boardworks Ltd 2001 Menu Penair School A B C Odd One Out? A5

© Boardworks Ltd 2001 Menu Penair School A B C x 1.5 x 2 Odd One Out? A5

© Boardworks Ltd 2001 Menu Penair School A B C Odd One Out? A6

© Boardworks Ltd 2001 Menu Penair School A x 2 B C x 3 Odd One Out? A6

© Boardworks Ltd 2001 Menu Penair School Guess the Scale Factor? ABCD x 2x 4x 3 x 5 B1

© Boardworks Ltd 2001 Menu Penair School Guess the Scale Factor? x 3 BCD x 2x 4 x 5 A B1

© Boardworks Ltd 2001 Menu Penair School Guess the Scale Factor? BCD x 2x 4x 3 x 5 A B2

© Boardworks Ltd 2001 Menu Penair School x 2 ACD x 3 x 4 x 5 B Guess the Scale Factor? B2

© Boardworks Ltd 2001 Menu Penair School Guess the Scale Factor? Need to be accurate here!!! BCD x 1.25x 2x 1.5 x 2.25 A B3

© Boardworks Ltd 2001 Menu Penair School Guess the Scale Factor? Need to be accurate here!!! BC x 1.25x 2x 1.5 A x 2.25 DB B3

© Boardworks Ltd 2001 Menu Penair School Drawing Enlargements Start with a point and a shape Draw lines to each point on the shape Scale Factor + 2 Multiply the length of each line by 2 Can you see the outline of the IMAGE? C1

© Boardworks Ltd 2001 Menu Penair School Drawing Enlargements Start with a point and a shape Draw lines to each point on the shape Scale Factor + 3 Multiply the length of each line by 3 Can you see the outline of the IMAGE? C2

© Boardworks Ltd 2001 Menu Penair School Drawing Enlargements Start with a point and a shape Draw lines to each point on the shape Scale Factor + 2 Multiply the lengths by 2 Note the outline of the IMAGE C3

© Boardworks Ltd 2001 Menu Penair School Enlarge this shape by... Scale factor + 2 Centre of Enlargement ( 1, 2 ) Multiply the length of each line by 2 Can you see the outline of the image? Drawing Enlargements C4

© Boardworks Ltd 2001 Menu Penair School Enlarge this shape by... Scale factor + 2 Centre of Enlargement ( 9, 10 ) Multiply the length of each line by 2 Can you see the outline of the image? Drawing Enlargements C5

© Boardworks Ltd 2001 Menu Penair School Finding Centres of Enlargement x Centre

© Boardworks Ltd 2001 Menu Penair School The Shape The Image Now draw the lines back to the... CENTRE OF ENLARGEMENT x Find the Centre of Enlargement? ( 1, 2 ) SCALE FACTOR + 2 D1

© Boardworks Ltd 2001 Menu Penair School The Shape The Image Now draw the lines back to the... CENTRE OF ENLARGEMENT x Find the Centre of Enlargement? ( 1, 0 ) SCALE FACTOR + 3 D2

© Boardworks Ltd 2001 Menu Penair School The Shape The Image Now draw the lines back to the... CENTRE OF ENLARGEMENT x Find the Centre of Enlargement? ( 5, 0 ) SCALE FACTOR + 3 D3

© Boardworks Ltd 2001 Menu Penair School The Shape The Image Now draw the lines back to the... CENTRE OF ENLARGEMENT x Find the Centre of Enlargement? ( 8, 1 ) SCALE FACTOR + 2 D4

© Boardworks Ltd 2001 Menu Penair School The Shape The Image Now draw the lines back to the... CENTRE OF ENLARGEMENT x Find the Centre of Enlargement? ( 7, 1 ) SCALE FACTOR + 0.5 D5

© Boardworks Ltd 2001 Menu Penair School WATCH THE ORDER CAREFULLY The Shape The Image x Why + 0.5 and not + 2 ??? ( 7, 1 ) SCALE FACTOR + 0.5 D5

© Boardworks Ltd 2001 Menu Penair School Fractional and Negative Enlargements x 0.5 E

© Boardworks Ltd 2001 Menu Penair School Fractional Enlargement 1 x divide all lengths by 3 1 3 E1

© Boardworks Ltd 2001 Menu Penair School Fractional Enlargement 2 x multiply all lengths by 0.75 3 4 E2

© Boardworks Ltd 2001 Menu Penair School Fractional Enlargement 3 x multiply all lengths by 0.6 3 5 E3

© Boardworks Ltd 2001 Menu Penair School Negative Enlargement 1 x -1 multiply all lengths by 1 and draw in the opposite (negative) direction. E4

© Boardworks Ltd 2001 Menu Penair School Negative Enlargement 2 x -1 multiply all lengths by 1 and draw in the opposite (negative) direction. E5

© Boardworks Ltd 2001 Menu Penair School Negative Enlargement 3 x -2 multiply all lengths by 2 and draw in the opposite (negative) direction. E6