The area between a curve and the [i]x[/i]-axis can be estimated using rectangles. [br]By adjusting the width of the rectangles and choosing which side they meet the curve, the estimate can be compared with the actual area.[br][list][*]Input a function. [br][/*][*]Select the number of rectangles using the slider[br][/*][*]Compare the rectangle area with the actual area. Notice the effect of reducing the width of the rectangles.[br][/*][/list]