Preview: Angle & Arc Relationships
As you adjust the circle and the secant lines, you will see the angle measures and the arc measures change.
When the lines intersect INSIDE the circle, the measure of the angles is half the SUM of the intercepted arcs (Theorem 12-13)!
When the lines intersect OUTSIDE the circle, the measure of the angles is equal to half the DIFFERENCE of the intercepted arcs (Theorem 12-14)!
As you adjust the circle and the secant lines, you will see the angle measures and the arc measures change.