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a)
(i) 9
(ii) 13
(iii) 16
b)
(i) 9 cm
(ii) 13 cm
(iii) 16 cm
8.
a) 28 m; 45 m 2
b) 6 cm
c) 4 km; 24 km
d) 7 cm; 28 cm 2
e) 11 m; 11 m
9.2
a) 15 000; 1.5
b) 37 500; 3,75
c) 24 000; 2,4
9.3
a) 15 000 000; 15
b) 9 000 000; 9
c) 37 500 000; 37,5
6. AREA
6.1 IMPORTANT to KNOW!
The area of a figure is the size of the flat surface that is included within the outside boundary of a figure. If you sweep your hand over this whole page, you have touched the whole surface of the page. If you paint a wall, we call the amount of space you have painted, the area.
6.2 Also IMPORTANT to REMEMBER:
Area is expressed in square units, e.g. square centimetre (cm2) or square metres (m2).
6.3 Memorise the following:
1 cm² = 10 mm x 10 mm = 100 mm²
1 m² = 100 cm x 100 cm = 10 000 cm²
1 km² = 1 000 m x 1 000 m = 1 000 000 m²
6.4 Ask your educator to photostat the following page or trace it just as it is:
a) Cut out the small squares and see how many of them will fit in the following figures.
__________________________________
__________________________________
__________________________________
b) What is the area of :
figure (i)? __________________________________
figure (ii)? _________________________________
figure (iii)? _________________________________
6.5.1 There is a quicker way to find out the area of figures!
We can use formulas,
e.g. rectangle
= length x breadth
= 5 x 2
= 10 cm2
6.5.2 Can you write down a formula that will determine the area of a square?
_____________________________________________________________________
7. Can you draw two different rectangles, each having an area of 48 cm²?
8. Work together with a friend and complete the following table:
| Length | Breadth | Perimeter | Area | |
| E.g. | 5 cm | 3 cm | 16 cm | 15 cm 2 |
| a) | 9 m | 5 m | ________ | ________ |
| b) | 6 cm | ________ | 24 cm | 36 cm 2 |
| c) | 8 km | ________ | ________ | 32 km 2 |
| d) | ________ | 4 cm | 22 cm | ________ |
| e) | ________ | ________ | 44 m | 121 m 2 |
9.1 Did you know?
The area of farms is calculated in hectares (ha).
1 ha = 100 m x 100 m
= 10 000 m²
9.2 Use your calculator and complete the following table:
| Lengthm | Breadthm | Aream 2 | Hectaresha | |
| E.g. | 100 | 100 | 10 000 | 1 |
| a) | 150 | 100 | ___________ | ___________ |
| b) | 250 | 150 | ___________ | ___________ |
| c) | 120 | 200 | ___________ | ___________ |
9.3 Complete the following with the help of your calculator:
| Lengthm | Breadthm | Aream 2 | Areakm 2 | |
| E.g. | 2 000 | 500 | 1 000 000 | 1 |
| a) | 5 000 | 3 000 | ___________ | ___________ |
| b) | 1 500 | 600 | ___________ | ___________ |
| c) | 7 500 | 5 000 | ___________ | ___________ |
Learning Outcome 4: The learner will be able to use appropriate measuring units, instruments and formulae in a variety of contexts.
Assessment Standard 4.2: We know this when the learner solves problems;
Learning Outcome 2: The learner will be able to recognise, describe and represent patterns and relationships, as well as to solve problems using algebraic language and skills.
Assessment Standard 2.3: We know this when the learner represents and uses relationships between variables in order to determine input and/or output values in a variety of ways.
Assessment Standard 2.5: We know this when the learner solves or completes number sentences by inspection or by trial-and-improvement, checking the solutions by substitution (e.g. 2 x - 8 = 4).
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