Example: Construction of 135 Degree Angle Video Lecture - Class 6

hello friends this video on practical
geometry part 13 is brought to you by
exam for your calm no more pure prom
exam now let's look at a little more
complicated angle you like 135 degrees
so how would you draw a 135 degree using
ruler compass first try to find out the
relationship of 135 degree with the
existing angles like how is 135 degree
related to 60 degree you are 120 degree
or 90 degree so try to find out some
relation now first look at it and find
where is it located now this angle lies
somewhere beyond 120 degree lies after
120 degree so we can say that it lies
between 120 degree and 150 degree in
fact it lies in the midpoint of these
two now the question is we know how to
draw 120 degree but we do not know how
to draw 150 degree so how can we draw
150 degree so if you take further 115
where is it located it is located
between 120 degree and 180 degree in
fact it is located exactly between 120
and 180 so what we are understanding is
in this case in this case we will have
two steps first step would be to draw
150 degrees how 150 degree lies exactly
between 120 and 180 so with this we will
draw 150 in step number two we will draw
135 degrees how 135 lies exactly between
120 and 150 so using these two things
using these two steps we will be able to
draw an angle of 135 degrees so let's
see so first we draw a 120 degree so for
120 degree again we do the same thing
first you take your Center as this point
o any convenient radius draw an arc then
you draw keeping the same radius draw
another
with be as the center so you would see
that this point intersects with existing
AG at some point C so when you join
point O and C you would get a 60 but we
are not interested in 60 DB for 120 what
we will do we consider C as the center
and the same radius again so we will see
that the new arc intersects at Point D
now when you join point O and point B
you would get a 120 degree so this angle
is going to be 120 degree and what is
180 degree 180 degree is straight angle
so this straight line makes 180 degree
this is 180 so that means this point
corresponds to 120 and this point
corresponds to 180 so let us call this
point as e so somewhere in exactly
between point D and E would lie angle
150 d that is our step number one so
let's do that with D as the center and
radius slightly more than half D we draw
an arc
similarly with he has the center and
radius slightly more than half D we draw
another arc and these two arcs they
intersect at some point F now the moment
we join point F 2.0 what is this angle
that we get so this angle that we get
exactly lies between 120 degree and 180
BD so this angle is 150 degree perfect
now we let's move on to step number 2 so
step number 2 is the angle between 150
and 120 so Point D corresponds to 120
and this point corresponds to 150 so
this point let's call this as G so
therefore take considering D as the
center and radius greater than half D G
that means the radius should be more
than the midpoint of D and G we draw an
arc
similarly with G as the center
and it is slightly more than half eg we
draw another art and we see that these
two arcs intersect at some point H now
when you join this point h 2.0 what is
it you get this angle this angle which
lies exactly between 120 and 150 so that
means this angle is 135 so in this
fashion you will be able to draw a 135
degree I am I agree that this is this
looks complicated but once you practice
doing these kind of construction for
various angles trust me it will become
simpler for you the only thing you need
to remember is you are not supposed to
specially for these type of
constructions of angles do not change
the orientation of the compass because
if you change that orientation you are
actually not going to get the correct
angle and whenever you do any
construction for an angle using the
ruler compass make sure that after you
have after once you are done with the
construction use a protractor to verify
if you have drawn the correct angle or
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