f = 3/r.
The formula for the volume of a cylinder is
V=πr²h. We know that h=2r, so this gives us:
V = πr²(2r) = 2πr³
The surface area of a cylinder is the sum of the areas of all of the faces. The bottom and top are circles, whose areas are both given by A=πr². The lateral area of a cylinder is given by the circumference multiplied by the height. C = 2πr, and the height is 2r, so the lateral area would be
A=(2πr)(2r)= 4πr². This gives us a total surface area of
SA = 4πr²+πr²+πr² = 6πr².
The ratio of surface area to volume would be:
SA/V = 6πr²/2πr³. After simplifying, we have f=3/r.
