The formula for the volume of a sphere is
V=4 out of 3 pi r^3.
How is this formula written if the radius,r,is a function of the volume,V?
V = (4/3)π r^3
so you want to solve for r
3V = 4π r^3
r^3 = 3V/(4π)
r = (3V/(4π))^(1/3)
or cuberoot(3V/(4π))