Areas of common shapes 225
Total area of brickwork = 48 + 12
= 60 m
2
.
Now try the following Practice Exercise
Practice Exercise 97 Areas of common
shapes (answers on page 351)
1. Name the types of quadrilateral shown in
Figure 25.18(i) to (iv) and determine for each
(a) the area and (b) the perimeter.
120 mm
30 mm
(iii)
26 cm
12 cm
16 cm
10 cm
(iv)
4 cm
(i)
5.94 cm
3.5 cm
6 mm
(ii)
30 mm
38 mm
Figure 25.18
2. A rectangular plate is 85 mm long and
42 mm wide. Find its area in square centimetres.
3. A rectangular field has an area of 1.2 hectares
and a length of 150 m. If 1 hectare =
10000 m 2 , find (a) the field’s width and (b) the
length of a diagonal.
4. Find the area of a triangle whose base is
8.5 cm and perpendicular height is 6.4 cm.
5. A square has an area of 162 cm 2 . Determine
the length of a diagonal.
6. A rectangular picture has an area of 0.96 m 2 .
If one of the sides has a length of 800 mm,
calculate, in millimetres, the length of the
other side.
7. Determine the area of each of the angle iron
sections shown in Figure 25.19.
7 cm
1cm
1 cm
(a)
(b)
2 cm
2 cm
30 mm
25 mm
8 mm
10 mm
50 mm
6 mm
Figure 25.19
8. Figure 25.20 shows a 4 m wide path around
the outside of a 41 m by 37 m garden. Calculate the area of the path.
41
4
37
Figure 25.20
9. The area of a trapezium is 13.5 cm 2 and the
perpendicular distance between its parallel
sides is 3 cm. If the length of one of the parallel sides is 5.6 cm, find the length of the
other parallel side.
10. Calculate the area of the steel plate shown in
Figure 25.21.
25
60
140
Dimensions
in mm
100
25
25
Figure 25.21