In calculating the vertical force component, you want to find the weight of the missing water.

This should be simple: Find the Volume of the missing water and multiply by specific weight.

Why is my volume calculation incorrect? I am using the volume of the rectangular prism whose top coincides with the surface and whose base coincides with B. Then I subtract the volume of the quarter cylinder:

[tex]V_{Tot}=V_{rect}-.25V_{cyl}[/tex]

[tex]V_{rect}=(1.5+0.75)(0.75)(1.2)[/tex]

[tex].25*V_{cyl}=.25*(\pi (0.75)^2(1.2)[/tex]

But this does not give the correct volume. The solution says to use:

I am failing miserably to see how my method is different from theirs? Am I messing up a dimension here?