Hydrostatics - submerged lamina

[cd19]

Homework Statement

Calculate the depth below the water surface of the centre of pressure of the water pressure acting on the submerged triangular lamina, height 3m, base 2m and located at a depth of 1m below the surface.

Homework Equations

not entirely sure

The Attempt at a Solution

I found the centroid location at 2.5m from the surface, c= (2)(3)^³/36.. now i have no clue what to do. any tips?, I now that the center of pressure must be below this point

 

[tjkubo]

Some vital information is missing from the problem statement.