QUESTION: A cylinder tank is 785 cubic feet. The height is 10 ft use the formula v=pi.r2.h to find the radius.
V=pi.r^2.h
785 = pi.r^2.10 -- divide both sides by 10
pi.r^2 = 78.5 -- divide both sides by pi
r^2 = 78.5/pi = 24.9873 -- now take the square root of both sides
r = 4.9987 ft
or, radius = 5 ft (approx)