Acylinder has a height of 8 feet and a volume of 628 cubic feet. find the radius of the cylinder. use 3.14 for π. show your work.

The formula for the volume of a cylinder is V=πr^2h

since you already know the height, volume, and pi, and you need to find the radius we can rearrange this formula to r^2 = Volume divided by 
(pi x (2xheight)). so r^2 = 628 / (3.14(2x8)).

r^2 = 628 / (3.14(2x8))  =  12.5 
r^2 = 12.5

now we need to find what r  is, all we need to do is square root r^2 so that we cancel out the "^2" 

the square root of 12.5 equals 3.53553390593
3.53553390593 rounds to 3.536. 

the radius of the cylinder is 5.536 feet
we can check our answer by plugging in our radius into the volume of a cylinder formula, which is V=πr^2h
so V = 3.14 x 3.536^2 x (2x8) = 628.17. or 628 when rounded, which you know is what the volume is.    this means that found the correct radius.