Calculus Applets with GeoGebra

Tangent Line as a Limit of Secant Lines

Instructions

  • Use the drop down menu to select a function.
  • The blue line is a secant to the function through points $A$ and $B$.
  • The green line is a tangent to the function through point $A$.
  • Drag points $A$ and $B$ to see how the slopes of the tangent and secant lines change.
  • Drag point $B$ closer to point $A$ and see what happens to the slopes of the secant and tangent lines as $B$ approaches $A$.