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Selina Solutions Class 9 Mathematics Solutions for Exercise 13(A) in Chapter 13 - Chapter 13- Pythagoras Theorem
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A man goes 40m due north then 50 m due west. Find his distance from the starting point.
Answer:
Solution:
Here, we need to measure the distance AB as shown in the figure below,
Pythagoras theorem states that in a right-angled triangle, the square on the hypotenuse is equal to
the sum of the squares on the remaining two sides.
Therefore, in this case,
Therefore the required distance is 64.03 m.
Video transcript
"hello students welcome to lido homework
i am tutor aaron bhatti from leader
learning now let us solve this
interesting question
a man goes 40 meter dew north
then 50 meter dew best
find the distance
from the starting point
as this is related with directions first
we will know how to write the directions
so i will draw it
here
always the top
will be our north
and below it will be south and in the
right side we have our east direction
and
the left is the west direction so for
this
question let us draw a reference diagram
so they have told the person
goes 40 meter from north so let
this point be a and it will be the
starting point from a he is moving
40 meters north so up
40 meters and let me
name this point as b
so the distance between a and b is 40
meter and next from
the point b he is moving 50 meters
west so from b
he is moving west by 50 meters
let me name this point as c
and this is 50 meters
the question is we have to find the
distance from the starting point
that is we have to
measure the distance from a to
c
so we have write the things what we have
done so let
a be the
starting point
and a b is equal to
40 meter and
c is equal to sorry bc is equal to
50 meter we have to
find the distance
between
a and c
now so here we could see
the directions where the person has
formed is forming a
right angled triangle so we could take
this as a
right angled triangle so in
a
right
angled triangle abc
by using the pythagoras theorem
we know that the square of the
hypotenuse side
will be equal to the sum of the square
of the other two sides that is
ac the whole square
is equal to
a b the whole square
plus
bc the whole square here we know
what is a b and b c so we'll get
ac the whole square is equal to
a b is 40 the whole square
plus bc is 50
the whole square now on squaring we'll
get
40 as
plus 50 the whole square will be
now on adding them we will get
ac the whole square
is equal to six
thousand hundred as we need ac
that is equal to root of six one
double zero on taking the square root
we will get ac is equal to
sixty four point zero
three therefore we have got our ac
as sixty
four point zero three
therefore the
required distances
sixty four point
meter if you have any questions please
post your questions in the comment box
and subscribe the channel for regular
updates
thank you
"
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