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in this video i'm going to show you how
you can find the perimeter of a circle
if you only know the diameter and to do
this i'm going to take you through a
simple work example we're going to look
at a circle that's got a diameter of 10
meters and calculate what the perimeter
of this circle would be and the first
step in being able to do this question
is to understand a simple definition
which is that for a circle the perimeter
of a circle that is the distance around
the outside has a specific name we call
that the circumference so that means
that we can use the circumference
formula and in maths we usually
represent the circumference with a
capital c and the formula is that the
circumference is equal to
pi
multiplied by the diameter
and we're already been told the diameter
so c is our circumference pi is actually
just a number and pi can be taken to be
3.141592 and so on it goes on forever if
you want to simplify you can just take
pi is 3.14 or you can find the button on
your calculator by finding the pi symbol
and that will take that number for you
so what we need to do is we need to look
at that equation copy it down again but
replace d
with the diameter which is 10 so we now
have the circumference is pi multiplied
by 10 you can actually leave that as
just 10 pi you've got pi times 10 you
now have 10 pi's
if you wanted to find the rough number
you might want to take pi is 3.14 and
that will simplify so you do 10 times
3.14 and that would give you 31.4
and because we've got the diameter in
meters the circumference is also going
to be in meters so there is our final
answer so i hope this video was helpful
to you and you can now calculate the
circumference or the perimeter of a
circle very quickly and easily thank you
very much for watching and please like
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