Topics
12. Geometry
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Australia
Year 6

12.08 Enlargements

Lesson
Practice
Lesson

Are you ready?

Do you know how a  translation, reflection or rotation  changes the position of a shape or object?

Examples

Example 1

Choose the picture that shows a reflection.

A
Two identical buckets next to each other.
B
Two identical combs where one is facing to the right and other one is rotated clockwise.
C
Two identical kangaroos, one is a mirror image of the other.
Worked Solution
Create a strategy

Choose the option that shows two objects that are mirror-images of each other.

Apply the idea

Option C is the correct answer because the two kangaroos are mirror-images of each other.

Idea summary

Translations, reflections and rotations change the position or orientation of the shape, but the shape itself stays the same.

Enlargement

An enlargement is another way to transform a shape or object. Let's learn more about them now.

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Examples

Example 2

The right rectangle is an enlargement of the left rectangle.

A blue rectangle with sides 2 and 4 centimetres, and a green rectangle with sides 6 and 12 centimetres.
a

What is the enlargement factor?

Worked Solution
Create a strategy

Divide the large rectangle's length by the small rectangle's length.

Apply the idea
\displaystyle \text{Enlargement factor}\displaystyle =\displaystyle \dfrac{12}{4}Divide the lengths
\displaystyle =\displaystyle 3
b

Write the scale of the small rectangle to the large rectangle.

Worked Solution
Create a strategy

Use the fact from part (a) that large rectangle is 3 times as large as the small rectangle.

Apply the idea

We can say that every 1 cm on the small rectangle is 3 cm on the large rectangle.

This means that the scale of the small rectangle to the large rectangle is given by:1:3

Idea summary

An enlargement keeps the same shape but changes the size of it.

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