The following applet approximates the volume of the solid generated by rotating the region of the xy-plane bounded by the curves y=f(x) and y=A for a ≤ x ≤ b about the horizontal line y=A. Simply enter the function f(x) and the values a, b, A and 0 ≤ n ≤ 100, the number of subintervals.

The values a, b and A can be changed by simply typing a new value, such as "1.2345", "pi/2", "sqrt(5)+cos(3)", etc. You may also change these values by using the up/down arrow keys, dragging the corresponding point left or right, or dragging the corresponding line up or down. To move the center of the graph, simply drag any point to a new location. To label the x-axis in radians (i.e. multiples of pi), click on the graph and press "control-r". To switch back, simply press "control-r" again.

You can rotate the object about the center of the screen by dragging the mouse while holding down the SHIFT key.

Here is a list of functions that can be used with this applet.