Year 9

# Area of similar shapes

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## Lesson details

### Key learning points

- In this lesson, we will identify similar shapes and subsequently work out areas of similar shapes using our knowledge of scale factors.

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### 5 Questions

Q1.

Fill in the gap: in two similar shapes, all corresponding _____ are equal.

Areas

Perimeters

Sides

Q2.

Triangles DEF and GHI are similar. What is the scale factor of enlargement if GHI is the object and DEF is the image?

0.3

1/3

2.5

Q3.

Triangles DEF and GHI are similar. What is the scale factor of enlargement if DEF is the object and GHI is the image?

0.3

2.5

3

Q4.

Are PQR and SPR similar?

No

Q5.

Are triangles PQS and SQR similar?

Yes

### 5 Questions

Q1.

The two rectangles below are similar. What is the scale factor of enlargement if the object is on the left and the image on the right?

2

3

3.5

Q2.

The two rectangles below are similar. What is the scale factor for the area if the object is on the left and the image on the right?

2

2.5

4

Q3.

The two rectangles below are similar. What is the scale factor of enlargement if the object is on the right and the image on the left?

0.16

16

4

Q4.

The two rectangles below are similar. What is the scale factor for the area if the object is on the right and the image on the left?

0.4

16

4

Q5.

Fill in the gap: to find the area scale factor, you must ______ the scale factor of enlargement.

cube

double

find the reciprocal