Tangent plane to an area (animation)

The applet shows the tangent plane at point P. Exercise Start the animation. Stop the animation, move the blue point P (in the xy-plane) and note how the tangents in x and y direction change. Select different views View towards xOy plane, View towards xOz plane and View towards yOz plane to study the area and the tangents. Analyse other functions in regard to their tangents in x and y direction Examples: f(x,y) = x*y f(x,y) = sin(x+y) f(x,y) = sin(x) sin(y)