Enlargements Flashcards

All 5 cards in this deck

What must you state to fully describe an enlargement?

The word "enlargement", the scale factor and the centre of enlargement.
e.g. enlargement, scale factor 2, centre $(0, 0)$

What are the steps to enlarge a shape by a scale factor from a given centre?
e.g. scale factor 2, centre $(0, 0)$

1. Count from the centre to a vertex, e.g. 3 right and 1 up.
2. Multiply by the scale factor: 6 right and 2 up — plot the image vertex.
3. Repeat for every vertex and join them up.

What happens to a shape when it is enlarged by scale factor $\frac{1}{2}$ from a centre?

The image is half the size, with each vertex's distance from the centre halved.

True or false? A scale factor of $\frac{1}{3}$ makes the shape smaller, so it is not called an enlargement.

False.
It is still an enlargement — scale factor $\frac{1}{3}$, and the image is three times smaller.

True or false? An enlargement by scale factor 3 makes all the angles 3 times bigger.

False.
Angles stay the same; only lengths are multiplied by 3, so the image is similar to the object.