Anybody know how to set this up?

The deep end of a swimming pool is vertical and has the shape of an isosceles trapezoid 6 m across the top, 5 m across the bottom, and 3 m deep. Find the force against the end.

I split the trapezoid in half, then integrated the rectangle and the triangle by themselves. When I added them together, I multiplied the result by 2 to get the force on the whole figure, but it is incorrect. I have tried working it 5 times, and keep coming up with the same thing. Maybe some fresh eyes will help out......

Thanks in advance for the help!