What theorem is dynamically illustrated in the applet below? [br](Feel free to move any of the points around.)
[b][color=#000000]Theorem:[/color][/b][br]The [b]measure of an angle[/b] formed by [b][color=#000000]2 chords[/color][/b] that intersect inside a circle is equal to half the sum (average) of the measures of their intercepted arcs. (The intercepted arcs are the [color=#ff00ff][b]pink arc[/b][/color] and the [color=#1e84cc][b]blue arc[/b][/color].)