This applet is designed to build intuition about tangent planes to
surfaces that are graphs of functions in two variables.
As with all major concepts in multi-variable calculus, this is done
seeing how this is connected to the related concept in calculus of one
- The applet has a control window and 3 graphics windows.
- There are windows for a y-z slice and an x-z slice, the two cross
sections of the 3-D graph obtained by holding x=x0 and y=y0,
respectively. On the control panel there are check
boxes to add the appropriate tangent line to each of these graphs.
- The third window gives a graph of the surface. If the
tangent lines are made visible on the slices, they will also be visible
here. An additional checkbox makes the tangent plane
visible. It should be noted that the tangent plane, if it exists,
is the plane that contains the two tangent lines for the slice curves.