L1 : Introduction - Perimeter and Area, Mathematics, CBSE Class 7 Video Lecture

hello friends this video on perimeter
and area part 1 is brought to you by
exam for calm no more fear from exam
topics to be covered in this lesson our
introduction parameter vs. area
perimeter and area of a square parameter
and area of a rectangle triangles as
part of rectangle area of a
parallelogram area of a triangle
circumference of a circle area of a
circle units conversion and applications
even before we understand what is
perimeter in area let's look at some of
these scenarios let's say that this is a
part of a village where each of these
families they have certain portion of
land for themselves now when you look at
this picture you see that there is a
vast stretch of land now the question is
how would each of these people like
let's let's assume that each house
belongs to a family so how would each of
the families know that how much portion
of the land is theirs ok so in order to
know that they need they actually need
to know how much part or how much region
is theirs now let's say that they got to
know that okay from starting from here
this much portion let's say till here
this part of the land is belongs to them
let's say this family got to know that
only this much portion of the land is
there now they want to put a boundary or
they want to fence this portion of the
land because it belongs to them so that
you know they can distinguish this part
from the remaining stretch of the land
so what do they do they need they need
to fence or they need to put a boundary
around this region so in this case in
order to do this entire thing the first
thing that they need to do is how much
portion is there so that is how much is
the area that is for them
the second thing they need to know is
what is the length of the boundary only
then they am
fencing right so like you see this is
done by let's say this house this family
has done this so they have put this
white colored fence so in order to put
this fence they need to know this length
only then you know they can bring the
wires or with whatever they want to put
that fence so in this case what do we
see we see that these are scenarios
where you need to know the area where we
need to know the length of the boundary
and area and perimeter these are the two
terms which are related to these
concepts let's look at another example
let's say you want to get a carpet
flooring done for a room in your house
or you want to laminate the door so how
would you do that now let's say if you
want to get a carpet flooring done for a
room so you just can't you know bring
without measurement you cannot do that
because your room might be a very small
room your room might be huge so the
measurement in terms of how much is the
area of the flow that is how much is
this region so that you know you can get
a carpet flooring done as per that
measurement so what do you need you need
the entire area or the entire region
that is covered by that particular room
in a similar way when you want to get a
door laminated so the entire area that
is covered by the door needs to be known
perfect so these are examples where we
use the concepts of area where we use
the concept of perimeter another example
let's say that you have a wire so the
while is definitely a straight wire and
you want to make that course a wire in
the shape of a square now why do you
want to do that maybe to make a frame
maybe you maybe you are trying to make a
photo frame so you just want to make the
base of the frame with this wire so now
how would you know if let's say that you
know the size of the square you need so
in that case you actually need to know
the length of the boundary of the square
so that you can this
side exactly how much length of the wire
do you need so what is this length of
boundary so whenever I am talking about
the total region covered that total
region covered is nothing but area as
you saw here or as you saw here but the
moment we talk about fencing like
putting a boundary so we are concerned
about the length of the boundary and the
moment we talk about length of the
boundary that is nothing but perimeter
so in these two scenarios when we are
talking about either fencing the field
or you know putting a wire in the form
of a square so we are basically
concerned about a perimeter so in this
lesson we are going to learn more about
area and perimeter and we are going to
talk about how to find area and
perimeter of different geometrical
shapes like square rectangle circle
triangles etc so let's get started so
first of all let us very quickly and
very clearly identify the difference
between perimeter and area so on the
screen you see different shapes like
triangle rectangle square by a hexagon
so these are all different polygons so
when we talk about parameter parameter
is nothing but the boundary of a closed
figure you consider any of these closed
figures the total length of the boundary
for example if you consider this
triangle so the length of the sum of the
lengths of the three sides gives you the
total length of the boundary similarly
if you talk about the square the sum of
the length of these four sides gives you
the total perimeter of the square or a
hexagon you have to sum up the lengths
of all the six sides and only then you
will get the perimeter of the hexagon so
parameter is nothing but boundary then
what about area the moment we talk about
area it is the entire region that is
occupied by the closed figure for
example again if you consider this
then this entire orange-colored region
the entire space which is enclosed by
the triangle that entire space is alien
so everything with inside the triangle
is nothing but area and what does
perimeter perimeter is just length of
the sides that is the total length of
the black colored lines is nothing but
perimeter so similarly can you tell me
what would which which region is the
area of this rectangle definitely this
yellow region similarly the green region
for the square the blue region for the
kite and the purple region for the
hexagon so these represent the area so
area is basically the entire space which
is enclosed by the polygon or any
geometrical shape whereas parameter is
the total length of the boundary so this
is a very simple and clear difference
between perimeter and area so thank you
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