Year 11
Higher

Find areas of similar shapes given corresponding lengths

Year 11
Higher

Find areas of similar shapes given corresponding lengths

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Lesson details

Key learning points

  1. In this lesson, we will use the linear scale factor to calculate the area scale factor and find areas of similar shapes.

Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

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3 Questions

Q1.
Shape A maps to shape B in an enlargement, calculate the scale factor.
An image in a quiz
-1
Correct answer: -2
1
2
Q2.
Why have corresponding vertices been joined up in shapes A and B with straight lines in this enlargement?
An image in a quiz
They do not do anything useful.
They get extra marks in a test.
Correct answer: They help with finding the centre of enlargement.
Q3.
The point at (-2,-1) is enlarged by a scale factor of -2 from the centre of enlargement at (0,0). What will the new coordinate of the point be?
An image in a quiz
(-4,-2)
(0,0)
(2,1)
Correct answer: (4,2)

4 Questions

Q1.
Shape A and shape B are similar. Calculate the area of shape B.
An image in a quiz
120 cm²
144 cm²
Correct answer: 240 cm²
30 cm²
Q2.
Two similar triangles have heights of 2 cm and 10 cm. The area of the smaller triangle is 5 cm². Calculate the area of the larger triangle.
10 cm²
Correct answer: 125 cm²
20 cm²
25 cm²
Q3.
Complete the missing word:
An image in a quiz
eight
four
Correct answer: sixteen
two
Q4.
Triangle A and triangle B are similar. Calculate the base length of triangle B.
An image in a quiz
12 cm
Correct answer: 16 cm
24 cm
4 cm