Firstly, start by inputing your chosen function into the box. The initial one is Sin(x).[br]Next grab the dark point which says 'Slide Me' and slide it. You will notice a trace outlining a graph. This graph is your derivative function. [br]The red text near the bottom is stating the f'(x) = y , so it tells you the X & Y values of the derivative function at that point.[br]Simply click 'Clear Trace' to remove the purple line.