An enlargement is a technical term for our next type of transformation. Don’t let the word fool you, because it won’t always make the shape bigger and it may move it.

With an enlargement we need a centre of enlargement from which we measure the enlargements and a scale factor.

So for instance, if the scale factor is two, we double the distance of every point on our shape from the centre of enlargement. If the scale factor is 1/3, we divide the distance of every point on our shape from the centre of enlargement by 3.

Let’s practice some (your teacher may use different scale factors to the ones given below, including scale factors smaller than one and negative scale factors).

Example

Also, as with the rotations, we will sometimes be shown the image and have to identify the centre of the enlargement and the scale factor of the enlargement. Let’s try doing that:

Exercise

Now let’s practice applying enlargements and also identifying enlargements:

The answers (for those questions requiring answers other than drawings) are given below:

Identifying the centre and the scale factor – exercise

Negative scale factors

If an enlargement has a negative scale factor, the image will be on the opposite side of the centre from the original image. We can practice this on the following linked page.