Answer:
The third one is the correct, we can rewrite r = sqrt(60/pi) as r = 2*sqrt(15/pi).
Explanation:
The area of a circle is given by the following formula:
area = pi*r²
Therefore the radius of a circle in function of it's area is given by the following:
pi*r² = area
r² = area/pi
r = sqrt(area/pi)
In this problem we have a circle with an area of 60 square centimeters, therefore the radius is expressed by:
r = sqrt(60/pi)
We can rewrite 60 as 4*15, so we have:
r = sqrt(4*5/pi)
Since sqrt(4) = 2, we can rewrite it as:
r = 2*sqrt(5/pi)
Therefore the write expression is the third one.