∠ACE is formed by two secants intersecting outside of a circle. If minor arc BD = 28°, minor arc AB = 112°, and minor arc DE = 112°, what is the measure of ∠ACE?
Minor arc AE =
360 - BD - AB - DE =
360 - 28 - 112 - 112 = 108”
And the measure of ACE = (1/2) [ minor arc AE - minor arc BD ] =
(1/2) [ 108 - 28 ] =
(1/2) [ 80 ] =
40°
