A dam is inclinded at an angle of 30 degrees from the vertical and has the shape of an isosceles trapezoid 100 feet wide at the top and 50 ft wide at the bottom and with a slant height of 70 ft. Find the hydrostatic force on the dam when it is full of water.

*The thing that keeps fooling me is when it says 100 ft at the top and 50 at the bottom, shouldn't those numbers be reserved to make an isosceles trapezoid?