Which equation correctly describes the relationship between the measures of the angles and arcs formed by the intersecting secants? m∠1=12(mAB−mCD)

m∠1=12mAB

m∠1=12(mAB+mCD)

m∠1=mAB+mCD
Circle with two chords. Point A at 10 o clock, point C at 2 o clock, point D at 3 o clock, and point B at 8 o clock are on the circle. Segment A D and segment B C intersect at a point. The angle made at the point of intersection of the two segments toward point A and B on the circle is labeled as 1.