Circle X is shown in the diagram. Circle X is shown. 2 chords intersect at a point to form arcs a and b. Arc a is intercepted by angle 1. Arc b is intercepted by angle 2. Arcs d and c are the other 2 arcs. Which equation can be used to solve for m∠1? m∠1 = One-half(a – b) m∠1 = One-half(a + b) m∠1 = One-half(c – d) m∠1 = One-half(c + d)