Enlargement
Making a shape bigger or smaller by a scale factor, from a fixed point called the centre of enlargement.
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Analogy
Like zooming in on a photo: the picture is the same shape at a different size.
Example
Point (2, 1)Multiply each coordinate by 3New point (6, 3)
In practice
Photocopiers and map scales use enlargement.
Practice
Flashcards
- Enlarge (2, 1) by scale factor 3 from the origin.(6, 3).
Questions people ask
What does a scale factor less than 1 do?
It makes the shape smaller, so the enlargement is really a reduction. A scale factor of 1/2 halves every length. The shape stays the same, just smaller. A scale factor of 1 leaves it unchanged. For example, a scale factor of 0.25 would shrink a 12 cm side to 3 cm.
How does enlargement change area?
If lengths are multiplied by a scale factor k, the area is multiplied by k squared. Doubling the lengths makes the area four times larger. Tripling lengths makes the area nine times larger. Volume grows even faster, by the scale factor cubed, because there are three dimensions to scale.