Two shapes are similar if the only difference between                        them is their size. Their side lengths are in the same proportions.

A property of a shape is invariant if that property has not changed after the shape is transformed.

Enlargement is a transformation that causes a change of size.

A scale factor is the multiplier between similar shapes that describes how large one shape is compared to the other.

The effect of enlargement on the area of a shape

Maths

In the prior unit, pupils enhanced their understanding of enlargement. In this unit, pupils investigate the effect of an enlargement on the perimeter and area of a 2-D shape and the volume of a 3-D shape.

Similarity

A pentagon is enlarged by scale factor 2. What properties of the pentagon and its image are invariant? 

The perimeter of rectangle B is 3 × the perimeter of rectangle A

The perimeter of rectangle B is 9 × the perimeter of rectangle A

The area of rectangle B is 3 × the area of rectangle A

The area of rectangle B is 6 × the area of rectangle A

The area of rectangle B is 9 × the area of rectangle A

Rectangle A has been enlarged to create rectangle B. Select the correct statements.

Rectangle A has been enlarged to create rectangle B. The area of rectangle B is {{ }} cm²

Trapezium B is an enlargement of trapezium A. Calculate the area of trapezium B.

Match each linear scale factor to the area scale factor.

Shape S is an enlargement an enlargement of shape R. The area of shape R is 32 cm². The area of shape S is {{ }} cm².

A scale factor is the multiplier between __________ shapes that describes how large one shape is compared to the other. 

This sector is enlarged by scale factor $$\frac{1}{2}$$. The angle in the image is {{}}°.

Each square on this coordinate grid is 1 unit long. This object is enlarged by a scale factor of 4 to make its image. Calculate the perimeter of the image.

A pentagon has a perimeter of 60 cm. The pentagon is enlarged by scale factor 7. The perimeter of the image is {{}} cm.

The object is enlarged by a scale factor of $$\frac{1}{3}$$ to make the image. What is the perimeter of the image?

A shape is enlarged by a scale factor of $$\frac{3}{2}$$ to make its image. The perimeter of the image is 42 cm. The perimeter of the object is {{ }} cm.

Starter Quiz