piecewise function problem describing area of figure

I'm completly stuck; i don't know where to begin. here's the question : write the piecewise function that describes the shaded area as a function of the height of the water, h.
here is an attached picture of the figure. http://i48.tinypic.com/im5ldh.jpg
thank you, help is greatly appreaciated!

Start by writing the formula for the area when h <= 8 and by reading about the area of a trapezoid. Show your work.