Drag the point along the [color=#0a971e]curve[/color] to find a spot where the slope of the [color=#1551b5]tangent line[/color] is equal to the slope of the [color=#c51414]secant line[/color]. Change the [color=#0a971e]function[/color] and interval to one of your choice. When you succeed in finding a point that works a congratulatory message appears.