Select the correct answer. the measure of an angle formed by two secants intersecting outside the circle equals a) 1/2 the sum of the intercepted arcs b) 1/2 the difference of the intercepted arcs c) 1/2 the measure of the intercepted arc

To answer this question you must know that there is a theorem called the "Two secants angle theorem", which establishes that the measure of an angle formed when two secants intersecting  outside the circle is equal to 1/2 the difference of the two intercepted arcs.

 Therefore, as you can see, the correct answer is the option B): B)1/2 the difference of the intercepted arcs