Similar Shapes

What’s the same & what’s different, with these pairs of shapes?

These shapes are similar: one of the shapes is an enlargement of the other.

What’s the same & what’s different, with these pairs of shapes?

These shapes are similar: one of the shapes is an enlargement of the other.

When we enlarge shapes, do the interior angles of the shape change?

When we enlarge shapes, interior angles don’t change, only the side lengths.

How has each shape been enlarged?

4 metres

8 metres

2 metres
6 metres

35°

35°

2 metres

4 metres

When we enlarge shapes, interior angles don’t change, only the side lengths.

How has each shape been enlarged?

4 metres

8 metres

2 metres
6 metres

35°

35°

2 metres

4 metres

Side Lengths × 2

Scale Factor of Enlargement: 2

When we enlarge shapes, interior angles don’t change, only the side lengths.

How has each shape been enlarged?

4 metres

8 metres

2 metres
6 metres

35°

35°

2 metres

4 metres

Side Lengths × 2

Scale Factor of Enlargement: 2

Side Lengths × 3

Scale Factor of Enlargement: 3

These are similar shapes.

What is the scale factor of enlargement?

DEMO

4 cm

Not to scale.

Similar Shapes

8 cm

These are similar shapes.

What is the scale factor of enlargement?

DEMO

4 cm

Not to scale.

Similar Shapes

8 cm

8
4= 2

Are these shapes similar?

4 cm

8 cm

8 cm

14 cm

Are these shapes similar?

4 cm

8 cm

8 cm

14 cm

We can compare corresponding sides.

Are these shapes similar?

4 cm

8 cm

8 cm

14 cm

We can compare corresponding sides.

Are these shapes similar?

4 cm

8 cm

8 cm

14 cm

We can compare corresponding sides.

Are these shapes similar?

4 cm

8 cm

8 cm

14 cm

We can compare corresponding sides.

The length has

a smaller scale factor of enlargement than the width.

The shapes are not similar.

First identify the two corresponding sides.

​Then find the scale factor.

Either multiply or divide by SF to find the missing length.

​Finding the missing length