Area under a curve
Enter your function and interval. Use the n slider to select the number of subintervals and the L-M-R slider to choose your sample points as left, right, or midpoints. Note that this illustrates the limit definition of the definite integral.
To change the viewing window, hold the shift button and left-click to drag the graph or use the scroll wheel to zoom in/out. You can also adjust the axes by holding the shift button and left-click on the axis you want to change.