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Knowledge of calculating the area of simple figures or shapes is an
essential skill for tradesmen such as carpenters, painters and builders.
Area is the measurement of the amount of space occupied by a closed
flat surface and is measured in square units. The most widely
used units of area are mm2, cm2
and m2. Land areas are often given in
hectares (ha).
1 ha = 10 000 m2
The following are applications of area:
- To calculate the number of tiles to be ordered to tile a kitchen
floor, the area of the kitchen floor must be taken into consideration.
- It is known that 5 litres of paint is needed to cover 50 square
metres. To calculate the amount of paint needed to paint a room,
we need to take into consideration the area of the walls, ceiling and
windows.
- To calculate the amount of glass required for a window, we need to
know the area of the window.
To the carpenter or carpet layer, who is concerned with the amount of
material to be used, measurement of area is very important.
Calculating the Area
In Year 7, you learned the following formulas for calculating the area of
plane figures such as squares, rectangles and triangles.
Example 1
Find the area of:
a. a square flower-bed of side 17 m
b. a rectangular field 45 m long and 40 m wide
c. a triangle of base length 30 m and height 25 m
Solution:
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Note:
To find the area of a region enclosed within a plane
figure, draw a
diagram and write an appropriate formula. Then substitute the given
values and use a calculator, if necessary, to obtain the required area.
Key Terms
area, square units, hectares
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