Fuel volumn in a cylinder tank when tank is more or less than half full

[Omar_Randel]

This problem was posed on a recent show. If the answer was arrived at, I didn’t hear it. All I need to know is the formula for the area of a portion of a circle that is less than half the circle

[Carveaholic]

http://www.cartalk.com/content/features/trucker-calculus/