a dam is inclined at an angle of 30 from the vertical and has the shape of an isoscales trapezoid 100ft wide on the top and 50ft wide at the bottom...

a dam is inclined at an angle of 30 from the vertical and has the shape of an isoscales trapezoid 100ft wide on the top and 50ft wide at the bottom and with a slant height of 70ft. find the hydrostatic force on the dam when it is full of water