The figure is basically an arc with a square underneath it with the top left and right side of the square touching the arc on either side. There is a line drawn from the center of the top of the arc to the bottom. 0 is at the bottom of the center line and x is at the bottom of the right line of the square. (x,y) is at the top of the right side of the square. f(x) is on the left side of the arc and square.
I know A=LxWxH. I'm not sure how to applies to A(x).