What is the radius of a circle whose circumference is $16π$ ?

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Answer 1 · 2015-11-24T23:43:43

$8$

The circumference of a circle is equal to $pi$ , which is a number $~~3.14$ , multiplied by the diameter of the circle.

Therefore, $C=pid$ .

We know that the circumference, $C$ , is $16pi$ , so we can say that:

$16pi=pid$

We can divide both sides by $pi$ to see that $16=d$ .

We now know that the diameter of the circle is $16$ .

We also know that the diameter has twice the length of the radius.

In equation form: $2r=d$

$2r=16$

$color(red)(r=8$

Note that since $2r=d$ , the equation $C=2pir$ holds and can be used in place of $C=pid$ .

What is the radius of a circle whose circumference is 16π16π?