How to obtain a Shape from a Given Net Video Lecture - (Maths) Class 7

let me draw a net of a solid this is the
net of a solid in which all six phases
are squares given the solid we have seen
how its net can be drawn but here we are
given the net and we have been asked to
find the solid it represents how do we
solve this
again it requires a little bit of
imagination the best way would be to
draw this net in a three-dimensional way
as if it's lying on a plane let's zoom
out and start with these four phases
first for it to seem as if they are
lying on a plane we can draw them a bit
like this one two three and four now it
seems as if they are lying on a plane
now on top of the second phase we have
another phase so we draw that square
face like this above the second one and
there is a square face attached to the
third square face this face at the
bottom will be drawn under the third
face clearly seems as if the net is
lying on a plane and it gives us a much
better idea about how the net can be
folded to form a solid how do we start
modifying the net to start off we can
fold these two faces inside and make
them vertical how will it look when
that's done let's draw the modified
figure on the right we draw these three
faces as this and these two are made to
stand erect this face when made vertical
will look like this yes now it seems as
if this face is vertical and these three
are lying on a plane and how will this
square face look when it's erect like
this and what about this face let's keep
it as is for now now let's try to make
these two faces vertical now pause the
video and try to draw the figure that
you will see when these two faces are
made vertical or at least try drawing it
mentally in your head
okay let's see how it will look these
two faces will still lie on the plane so
we draw these two faces first these two
faces which are erect can be drawn asses
like this and like this and now we make
these ones vertical this face when
straightened will look like this and
this one went straight and will look
like this
this is the shape we have arrived at
after making these four faces vertical
now if we just rotate this section
towards the left can you tell me what
solid we will get yes we will get a cube
a cube which will look like this
remember all the faces were squares and
the net was folded in such a way that we
got a cube so here we converted a net to
its solid
here's another simple example for you to
try out this is the net given to us a
square with four congruent isosceles
triangles each attached to one of its
sides what solid shape can we form out
of it pause the video and try to draw
this figure as if it's on a plane
okay so how about we draw the square
first to show that it lies on a plane it
can be drawn like this these four
triangles will also lie on the same
plane triangle one triangle to triangle
three and triangle four we have just
tilted this to make it lie on a plane
and now it becomes much easier for us to
think of the solid that can be formed
out of this net we just have to rotate
each triangle such that all the top
vertices meet at a single point what we
get is a square pyramid
a square as the base and four triangles
as its faces is it always this easy to
convert Nets to solids we will see an
interesting example next
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