Area of a circle = pi • r^2
We need to isolate for r.
A/pi = r^2
r = sqrt(A/pi)
r = sqrt(30.8/pi)
r = 3.1311251164
Diameter = 2r
Diameter = 6.26225023
Diameter = 6.3 m
x is the variable
<em>In mathematics, a variable is a symbol; in this case, X.</em>