Perpendicular bisector - Triangle and Its Properties, Mathematics, CBSE Class 7 Video Lecture

hello friends this video on triangle and
its properties part four is brought to
you by exam for calm no more fear from
exam now many times people feel that
million and perpendicular bisector they
are the same thing but actually these
are very much different from each other
now even before I talk about how they
are different let us look at what
exactly is a perpendicular bisector so
when we say perpendicular bisector
perpendicular means a line which makes
which is perpendicular to a particular
sign that means the line which is which
makes an angle of 90 degree on a
particular line so that is perpendicular
fine bisector means a line which bisects
another line that means it bisects or
divides another line into two equal
parts now if I say perpendicular
bisector of a side of this triangle let
us name this triangle let us say you
have this triangle ABC and let us say I
want to draw the perpendicular bisector
of side BC so what would be the
perpendicular bisector of BC it would be
a line which divides BC which bisects BC
into two equal parts so let us say this
is the midpoint of BC and also that line
should be perpendicular to BC so
basically somewhat like this so if we
draw a line like this which is
perpendicular to BC and which also
divides BC into two equal halves that is
called a perpendicular bisector and by
now we know what is median median is
that line which joins this midpoint of
BC to the vertex a so that would be
medium now what happens is that in
certain triangles for example this
triangle which is actually an exception
so in some exceptional triangles what
happens is the median and the
perpendicular bisector they
inside now this happens as a special
case of a triangle where all the sides
are equal what type of triangle is that
yes equilateral triangle so in an
equilateral triangle it can happen that
the perpendicular bisector and chameleon
they coincide so that is basically they
both are represented by the same line
but that doesn't mean that a
perpendicular bisector
I am the median they will always
coincide now let me give you an example
of a triangle like this so what kind of
triangle is this this is an obtuse angle
triangle right because we have an obtuse
angle here now for this triangle if I
ask you to draw the perpendicular
bisector for side BC so how would the
perpendicular bisector be for side BC it
has to be a line which bisects BC right
and it should also be perpendicular to
BC so something of this sort let's say
this is the midpoint of BC let us call
this point as O so perpendicular
bisector would be perpendicular that is
it will be 90 degrees on BC and also it
divides BC into two equal halves Bo and
OC 3 and so this is the perpendicular
bisector now do you think that the same
line that is this line is also going to
be the median definitely not because
medium is that line which joins the
midpoint of BC to the vertex that is 2.8
so basically the median for the same
triangle would be somewhat like this so
basically this is your median so do you
think that in this strangle the medians
the median and the perpendicular
bisector in any way coincided no they
both are completely different lines so
they are completely different from each
other so this is one example where we
see that the perpendicular bisector and
median these are two different lines
these are two different things
you take another example let us talk
about this triangle which is a
right-angled triangle so you have a 90
degree here now if I ask you to draw a
perpendicular bisector on BC that would
be somewhat like this again a line which
is perpendicular and on BC and which
also divides or bisects BC that is it it
is drawn at the midpoint of BC now do
you think this line is going to be the
median for the same triangle definitely
not again when you take the same
triangle and you draw the median median
is that line which is going to join the
vertex to the midpoint so median is a
separate line so it is just in some
special case where the perpendicular
bisector and the median coincide but
otherwise these are two different
concepts these are two different lines
they are completely different things
they are not the same thing right so
that's about medium so here we are
learning about median and I want you to
know how different median is from
something like a perpendicular bisector
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