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We are ask to find the complete distance all around this circle here and there is more
than one formula for working out that circumference and I am going to write down both of them.
And the first one is – were we have pi approximated to 3.14 -- that is the value of pi now the
radius in this particular example does not seem to be here because we are not given a
radius we are not given a diameter all the way across 15cm, now if you want to find radius
you know you got to half the diameter and that will give you the radius but if you want
to do it quickly you just go into the second formula which is as follows – ah, that is
much better because we are given a diameter in this particular example and the diameter
here in this particular example and the diameter in this example happens to be 15cm all we
need to do is plug and play it into this formula and we can work out the total distance around
here. So let us do that now, so Circumference = pi
which is 3.14 so let us write that in – and the diameter 15cm – all we need to do now is multiply 3.14 x 15 that is going to
yield a distance of all the way around here the complete circumference is c=47.1cm.
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