Hello, Jonboy!
A crosssection of an irrigation canal is a parabola.
If the surface of the water is 40 feet wide and the canal is 35 feet deep at the center,
how deep is it 10 feet from the edge? I must assume that the canal is full of water.
The crosssection can be graphed like this: Code:

*     +     *(20,35)
::::::::::::::::::::
*::::::::::::::::::*
*::::::::::::::::*
*::::::::::::*
*::::::*
     *       

The equation of this parabola is: .
Since (20,35) is on the curve: .
And the equation is: .
When
And the depth of the water is: .