A circle is shown. 2 secants intersect outside of the circle to form angle 1. the measure of the first arc formed is b degrees, and the angle of the second arc is a degrees. arc c degrees is outside of the secants. which formula would be used to find the measure of angle 1? one-half(a� b�). one-half(a� � c�). one-half(b� c�). one-half(a� � b�).