What geometry theorem is dynamically being illustrated in the applet below? [br](Feel free to move any of the points anywhere you'd like!) [br]Note: The [color=#1e84cc]blue ray[/color] shown is a [color=#1e84cc]tangent[/color].)
[color=#000000][b]Theorem:[/b][/color][br]In a circle, the [color=#ff00ff][b]measure of an angle[/b][/color] formed by a [color=#1e84cc][b]chord[/b][/color] and [color=#1e84cc][b]tangent[/b][/color] is equal to half the measure of the [color=#ff00ff][b]arc[/b][/color] it intercepts.