Question

What is the measure of angle s?

Answer 1

The angle formed by the intersection of two secants outside the circle equals half the difference of the intercepted arcs:

m∠S = (80-40)/2 = 40/2 = 20°

Answer 2

m<S = 1/2(80-40)
m<S = 40/2
m<S = 20
answer is A. 20