A metal oil tank has cross-section that is a square rotated 45 degrees as shown in the figure above. Its height is 12 ft and width is 12 feet. The oil in the tank has a weight-density of 57 lb/ft3. Write a definite integral that expresses the fluid force on the end of the tank when the oil is 4 feet deep? Here is a link to the photo : http://img17.imageshack.us/img17/2294/76984288.jpg [Broken] hopefully you can make it out. I am not sure how to set up the definite integral.