Circles Exterior Angles

Manipulate points B, C, and D to determine the relationship between an angle formed by two chords intersecting outside of a circle and the measures of the intercepted arcs.

If an angle is inside a circle, you add the two intercepted arcs together and divide by 2 (find the average). How might that process be different if the chords form an angle outside of the circle? [i]Hint: the two methods are closely related.[/i]