What is the diameter of a circle whose area is $16$ $pi$ ?

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Answer 1 · 2015-12-25T02:39:28

$8$

Use the formula for the area of a circle:

$A=pir^2$

Here, the area is $16pi$ :

$16pi=pir^2$

Divide both sides by $pi$ :

$16=r^2$

Take the square root of both sides:

$sqrt16=sqrt(r^2)$

$4=r$

Since the radius of the circle is $4$ , the diameter is twice that:

$d=4xx2=8$

Answer 2 · 2018-08-08T02:20:32

$8$

Recall the formula for the area of a circle:

$A=pir^2$ , with radius $r$

We see that our radius is $sqrt16$ , or $4$ .

Recall that the diameter is twice the length of the radius, so we can multiply this by $2$ to get a diameter of $8$ .

Hope this helps!

What is the diameter of a circle whose area is 1616pipi?