Enlargments
Enlargement is a transformation that produces an image (new shape) that is the same shape
as the original figure but a different size. It may increase or decrease the size, depending on
the scale factor. The scale factor can be positive, negative and a fraction. They all have
different meanings.
Apart from the scale factor we will be also given the centre of enlargement. The fixed point
about which the shape is enlarged. Every point on the original figure moves away from or
towards this point.
Steps for doing enlargements
1. Identify the centre of enlargement. This is usually given in the question. It is
suggested to mark it down on your graph.
2. Measure the distance in terms of boxes from the centre to each point of the original
shape.
3. Multiply each distance by the scale factor. (Ideally you show some working as well)
4. Plot the new points in the same direction (or opposite for negative scale factor).
5. Join the new points to form the enlarged image.
If the scale factor is greater than 1, it means that the shape is getting bigger. If the scale factor
is a fraction, it means that the shape is getting smaller. If the scale factor is a negative, the
new image is projected backwards.
Example 1
Enlarge the triangle by a scale factor of 2 where the centre of enlargement is (0,0).
, Example 2
Enlarge the blue triangle by a scale factor of -1. The centre of enlargement is (-2,2)
Enlargement is a transformation that produces an image (new shape) that is the same shape
as the original figure but a different size. It may increase or decrease the size, depending on
the scale factor. The scale factor can be positive, negative and a fraction. They all have
different meanings.
Apart from the scale factor we will be also given the centre of enlargement. The fixed point
about which the shape is enlarged. Every point on the original figure moves away from or
towards this point.
Steps for doing enlargements
1. Identify the centre of enlargement. This is usually given in the question. It is
suggested to mark it down on your graph.
2. Measure the distance in terms of boxes from the centre to each point of the original
shape.
3. Multiply each distance by the scale factor. (Ideally you show some working as well)
4. Plot the new points in the same direction (or opposite for negative scale factor).
5. Join the new points to form the enlarged image.
If the scale factor is greater than 1, it means that the shape is getting bigger. If the scale factor
is a fraction, it means that the shape is getting smaller. If the scale factor is a negative, the
new image is projected backwards.
Example 1
Enlarge the triangle by a scale factor of 2 where the centre of enlargement is (0,0).
, Example 2
Enlarge the blue triangle by a scale factor of -1. The centre of enlargement is (-2,2)
