Enlargements
Maths: Edexcel IGCSE Higher, topic 5.2.4
Describing Enlargements
Transformation can be used to describe how a shape or point moves on coordinate axes.
Describing an enlargement
- A scale factor and a centre of englargement are required to describe an enlargement.
- The scale factor tells you how many times larger the image is compared to the object.
- The centre of enlargement tells you where the enlargement centres around.
- The centre of enlargement affects where the image of the enlargement goes.
Find the scale factor
- Work out how many times bigger the image is compared to the object to find the scale factor, S.
- You can do the scale factor by finding how many times bigger the image is compared to the object.
Fractional scale factors
- It is possible for an image to be smaller than an object when completing an enlargement.
- The image will be smaller is the scale factor is between 0 and 1.
- E.g. if an object is enlarged by scale factor then all the lengths in the image will be the length of the corresponding (matching) lines in the object.
Find the centre of enlargement
- Draw lines connecting corresponding (matching) points on the image and object.
- Where these lines cross is the centre of enlargement.
Test yourself on Enlargements
What happens to the image compare to the object when you enlarge by a fractional scale factor?