Checking and securing understanding of enlargement with positive integer scale factors | Starter Quiz | Oak National Aca

A (a)   of a shape is the mirror image of the shape.

Answer explanation

A reflection of a shape is the mirror image of the shape. An object is reflected when it is flipped over a fixed line (called the line of reflection), without the image being turned or its size changing.

Which of these diagrams do NOT show a reflection?

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Answer explanation

In choice 2, the object and image are not the same distance from the line of reflection. Choice 1 shows a rotation and not a reflection as the image has turned.

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

• angles

• orientation

• position

• size

• vertices

Answer explanation

Two shapes are shapes if the only difference between them is their size. Their side lengths are in the same proportions this means that one shape is an enlargement of the other.

Which of these diagrams show a reflection?

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Answer explanation

An object is reflected when it is flipped over a fixed line (called the line of reflection), without the image being turned or its size changing. Choices 1 and 4 show a rotation.

Rectangle B is an enlargement of rectangle A by scale factor 2. Rectangle A has perimeter = 18 cm and area = 18 cm². Both rectangles have integer side lengths. Find the area and perimeter of B.

• Area = 36 cm²

• Area = 72 cm²

• Perimeter = 36 cm

• Perimeter = 72 cm

Answer explanation

3 cm × 6 cm = 18 cm² and 3 cm + 6 cm + 3 cm + 6 cm = 18 cm. So rectangle A is 3 cm by 6 cm. Therefore rectangle B is 6 cm by 12 cm. The perimeter of B is 6 cm + 12 cm + 6 cm + 12 cm = 36 cm and the area of B is 6 cm × 12 cm = 72 cm²