L5 : Quadrilaterals - Quadrilaterals , Maths, Class 8 Video Lecture - Class 8 | Best Video for Class 8

hello friends this video on
quadrilaterals part 5 is brought to you
by exam feel calm no more fear from exam
what we are going to study in this
lesson are the quadrilaterals that is
the polygons with four sides now in
quadrilaterals also we will see that
there are many different categories of
quadrilaterals so let's understand what
they are now even before we start
learning about quadrilaterals you might
be interested to know why do we need to
study quadrilaterals why and how will it
help me so let us try to connect it with
our day-to-day life as I already
mentioned that there are so many shapes
there are so many objects that exist
around us and all of them have some
other other shape in that you would be
amused amazed to see that there are many
shapes around us which are nothing but
quadrilateral let's think of your
blackboard the shape of your blackboard
is nothing but a quadrilateral think of
the laptop screen or the desktop screen
so the shape of the screen again is a
quadrilateral think of a book or a
windowpane or even the kite so all these
are in the shape of quadrilaterals a
table TV the bed so hope all of these
when you look at their shapes so when
you look at this TV screen this is a
quadrilateral you look at the window pin
this is again a quadrilateral you look
at your blackboard that is again of
water lateral you look at their bed so
that's again a quadrilateral
now you might next ask me that okay fine
even if these objects have the shapes of
quadrilaterals fine I got to know that
okay this is a quadrilateral and that
should be fine why are we digging in
more to know more about quadrilaterals
because if we know quadrilaterals in
depth we can decide certain things with
regards to such objects let's say that
now beds can be of many different sizes
right now even though the shape
shape of the bed would be a
quadrilateral always but their sizes
would value now if I ask you that what
should be the size of the bedsheet that
you would need for your bed now in order
to answer that you need to know the size
of your bed so how do you know the size
of your bed with the dimensions like so
you need to know the dimensions of your
bed you need to know the area that your
bed includes the area that is enclosed
by the boundary of the bed similarly if
you have a field which is again in the
shape of quadrilateral if I ask you that
how much wire do you need to fence that
field
now for that again you need to know how
much is the total boundary of that field
so to make such calculations to maintain
all these decisions you need to have a
detailed idea on what quadrilaterals are
like you need to know the size of your
bed for buying a bed sheet similarly you
need to know the size of your mobile
phone to buy a mobile cover you need to
know the size of your window to buy
curtains you need to know the size of
the field field in order to fence it so
knowing these dimensions like area
shapes etc would help so when we talk
about quadrilaterals we are not only
going to talk about the shape as such we
are going to talk about the various
types of quadrilaterals their area they
are boundary and what are their
properties so those are the things that
we will touch upon so what are
quadrilaterals these are polygons with
four sides now on the screen you can
already see up you can see many
varieties of in the shapes of polygons
even though all of them I have four
sides now in any quadrilateral what are
the things that we have in common we
have four sides we have four vertices we
have four internal angles so think of
consider any of these so you have four
internal angles like these you have four
sides like these
you also have the four vortexes that's
these points but now these are the
things that could be common that all of
them will have four sides all of them
will have four internal angles all of
them would have four vertices now what
would vary is there could be a variation
in these parameters in the values of
these parameters now in certain
quadrilaterals all the internal angles
might be equal in certain for certain
quadrilaterals there are two internal
angles would be equal in some of them
none of them would be equal right
similarly in some of them the sides
might be parallel in some sides will be
not parallel in some sites will be equal
in some sites will be unequal then some
angles will be equal in some angles will
be unequal so basically depending on
these kind of parameters we would see
that there exist many different types of
quadrilaterals so even before we talk
about the different types of
quadrilaterals let us talk about some
now even before we talk about the
different types of quadrilaterals let us
talk about some of the basic properties
of quadrilateral so the four thank you
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