Examples: Triangles Video Lecture | Mathematics for Grade 6

hello friends this video on
understanding elementary shapes part 14
is brought to you by exam for calm no
more pure from exam so now that we have
learnt about the various types of
triangles we will try some questions
question number one
name the types of following triangles
triangle l m n with angle L this M angle
L means measure of angle L is equal to
30 degree measure of angle M is equal to
70 degree and measure of angle n is
equal to 80 degrees so let us try to
draw a rough sketch of this triangle so
angle n is 30 degrees so first we draw
and well L let's say this is 30 degree
and this is angle N and then M is 70
degree so let's say that this let's call
this point as this is l m n so now when
we join this triangle we see that this
angle M is 70 degree and this angle n is
8pd now these are not accurate
measurements we are just drawing a rough
triangle so what do we see the
measurement of all the three angles are
less than 90 degree that means what type
of triangle is this this is an acute
angle triangle now since there is no
mention about the sides so we will not
be able to decide whether it is a
scalene triangle or an isosceles
triangle so we will not mention anything
about that next one is angle XYZ
triangle XYZ with angle Y is equal to 90
degrees let's draw a 90 degree so this
is 90 degree and this is angle Y and X Y
is equal to Y Z so if this is X and this
is Z so X Y is equal to Y Z so what type
of triangle is this so here there is one
and the 90 degree but so this this has
to be a
triangle at the same time two sides are
also equal so this is an isosceles
triangle so this is right-angled and
socialist triangle question AMA to name
each of the following triangles in two
different ways
you will judge the nature of the angle
by observation because just by
observation we have to tell which
triangle is of which type so the first
triangle we see all the measurement of
the three sides are different so that
means this is a scalene triangle but at
the same time regarding the angles we
see that there is one angle which is 90
degree so that means this is a
right-angled scalene triangle let's look
at the second one here we see that the
length of these two sides are equal both
are 7 centimeters so that means it is an
isosceles triangle and we also see that
the measure of this angle is greater
than 90 degree because 90 degree would
have been somewhat like this so it is
more than 90 degrees that is this is
obtuse angles so this is obtuse angle
also see the strangle
question number 3 which of the following
are models for perpendicular lines now
what do we mean by perpendicular lines
that means when two lines intersect each
other at 90 degrees they are said to be
perpendicular on each other let's say
there is one line like this there is no
other line like this so both the lines
are intersecting at this point and also
the angle that they make at the point of
intersection is 90 degrees so we can say
that these lines are perpendicular to
each other so the adjacent edges of a
tabletop so if you look at the table
talk you would see that that this this
side and this side these are the absent
edges the adjacent sides so are they
perpendicular to each other yes they are
because when you look at a tabletop the
tabletop is like
angular in shape if BR talking about the
general rectangular tabletop so in that
case they're artisan sides are
perpendicular to each other the lines of
a railway track well when you talk about
the lines this is one line and this is
another line and these two lines they do
not seem to be inter intersecting each
other so these two lines are parallel to
each other so two parallel lines cannot
be perpendicular to each other because
they are not going to meet itself and
for two lines to be perpendicular the
first criteria is that the two line
should intersect and that two at 90
degree so therefore the lines of a
railway track are not models of
perpendicular lines let's look at the
next one the line segments forming the
letter L so if you focus properly on the
letter L of the English alphabet you see
that this line is perpendicular to this
line because both the lines intersect at
this point and that too at 90 degree so
yes they are a model of perpendicular
lines the letter V so if you look at
letter V here also these two lines
intersect at this point but the angle at
which they intersect is an acute angle
so this is not a perpendicular line
question number four there are two set
squares in your geometry box what are
the measures of the angles that are
formed at their corners do they have any
angle measure that is common now if you
look at the two sets squared you would
see that both the set Square has 90
degree in common so for this set square
this is 90 degree this is 60 degree and
this is 30 degree so this is one piece
of Seck square where the other tool
angles except the 90 degree they are
unequal one is 60 the other one is 30
whereas the other another set where one
angle is
and the other two angles are also equal
so they and 45-degree 45-degree each so
which angle is common amongst them so 90
degree is common so one set square has
90 60 30 the other set Square has 90 45
45 so which is the common angle 90
degree is the common angle between them
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