Basic Engineering Mathematics, Fifth Edition

Areas of common shapes 225

Total area of brickwork= 48 + 12

=60m^2.

Now try the following Practice Exercise

PracticeExercise 97 Areas of common

shapes (answers on page 351)

1. Name the types of quadrilateral shown in
   Figure25.18(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 85mm long and
   42mm wide. Find its area in square centi-
   metres.


3. Arectangular field hasanareaof1.2hectares
   and a length of 150m. If 1hectare=
   10000m^2 ,find(a)thefield’swidthand(b)the
   length of a diagonal.


4. Find the area of a triangle whose base is
   8 .5cm and perpendicular height is 6.4cm.


5. A square has an area of 162cm^2. Determine
   the length of a diagonal.


6. A rectangular picture has an area of 0.96m^2.
   If one of the sides has a length of 800mm,
   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.

7cm

1cm

1cm

(a) (b)

2cm 2cm

30 mm

25 mm

8mm

10 mm

50 mm

6mm

Figure 25.19

8. Figure 25.20 shows a 4m wide path around
   the outside of a 41m by 37m garden. Calcu-
   late the area of the path.

41

4 37

Figure 25.20

9. The area of a trapezium is 13.5cm^2 and the
   perpendicular distance between its parallel
   sides is 3cm. If the length of one of the par-
   allel sides is 5.6cm, 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