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More geometry, data handling and probability

Educator section


3 cm 2 cm 10 cm 6 cm
6 cm 4 cm 20 cm 24 cm
9 cm 6 cm 30 cm 54 cm
15 cm 10 cm 50 cm 150 cm
3. (a)

(b) 2 twice more; 3 times more;

5 times more than first rectangle

(c) 16 times

4.2.1 – 4.2.4 Check learner’s effort.

Leaner section


Activity: compare sizes [lo 4.2, lo 3.8]


The following rectangle has been enlarged first two times, then three times and then five times.

All the rectangles have the same ratio for length to breadth: 3:2.

a) Look again at the rectangles above. Suppose that each block is 1 cm by 1 cm. Complete the table.

Rectangle Length Breadth Perimeter Area
1 __________ __________ __________ __________
2 __________ __________ __________ __________
3 __________ __________ __________ __________
4 __________ __________ __________ __________

b) What happens to the perimeter each time the rectangle is enlarged?



c) How many times larger is the area if the rectangle is enlarged four times?


4.1 Did you know?

The ratio to scale is always written in a specific way:

The first number refers to the drawing/plan.

The second number refers to reality.

A scale of 1:5 means that the length is 5 times smaller than in reality.

A scale of 5:1 means that the length is 5 times bigger than in reality.

4.2.1 Use the graph paper and enlarge the sketch on a scale of 4:1.

4.2.2 Enlarge this drawing on a scale of 1:2.

4.2.3 Reduce this sketch on a scale of 2:1.


  • Can you enlarge this drawing and re-draw it?


Learning Outcome 3: The learner will be able to describe and represent characteristics and relationships between two-dimensional shapes and three-dimensional objects in a variety of orientations and positions.

Assessment Standard 3.8: We know this when the learner locates positions on co-ordinate systems (ordered grids) and maps

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.

Questions & Answers

Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Mathematics grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11075/1.1
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