How do we calculate the (signed) area under a curve, say y = f(x) which is bounded by x=a to the left, x = b to the right, and the x-axis? Click the check boxes and adjust the number of boxes n and location of the sample point to see various approximations of the area.

How to use this demo:
- Drag a and b along the x-axis to change the left- and right-hand sides of the definite integral.
- Change n by dragging the slider back and forth to change the number of boxes in the approximation.