year 8 maths

180 Chapter 3 Measurement and Pythagoras’ theorem
7 The size of a television screen is determined by its diagonal length. Find the size of a television
screen that is 1.2 m wide and 70 cm high. Round the answer to the nearest cm.
8 Here is a diagram showing the path of a bushwalker from camp 1 to camp 2 . Find the total
distance, calculated to one decimal place.
Camp 1
3 km
2 km
Camp 2
1.5 km
9 A 20 cm straw sits in a cylindrical glass, as shown. What length of straw sticks above the top of the
glass? Round the answer to two decimal places.
14 cm
4 cm
10 Explain the error in each set of working.
a c 2 = 2 2 + 3 2
∴ c = 2 + 3
= 5
b c 2 = 3 2 + 4 2
= 7 2
= 49
∴ c = 7
11 Prove that these are not right-angled triangles.
a 5
b
c c 2 = 2 2 + 5 2
c 12
= 4 + 25
= 29
= √29
7
3
8
10
24
21
5
ENRICHMENT
– –
12
Perimeter and Pythagoras
12 Find the perimeter of these shapes, correct to two decimal places.
a
b
10 cm
2 m
18 cm
c
7 cm
3 m
4 cm
d
6 mm e
f
4 mm
5 m
8 mm
2 m
Cambridge Maths NSW
Stage 4 Year 8 Second edition
ISBN 978-1-108-46627-1 © Palmer et al. 2018
Cambridge University Press
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