How it works ?
Displayed below is the graph of f (x) = tan (x)
The y-coordinate of the blue point = the slope of the line tangent to the graph of f at the BIG WHITE POINT.
Drag this BIG WHITE POINT around to observe the graph of the derivative of function f being traced out.
Without opening up another tab in your browser to look it up, feel free to take a guess as to what the derivative of this function might be. (You don’t have to do this right away, but you will eventually in the questions that follow.)