This applet shows the graphs of a function f, its first derivative f'. A tangent line is drawn on the graph of f and f'. The x-coordinate of the point of tangency is controlled by an input box and a slider below the graphs. The formula for the derivative function is displayed at the bottom of the applet. The user may enter functions of this form in the "f(x)=" input box. See also, the first and second derivatives applet.