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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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