AB and CD are two chords of a circle that intersect at a point E. Arc AC has an arc measure of 84° and arc DB has an arc measure of 20°. What is the measure of ∠AED?
Angles of Intersecting Chords Theorem :
Angle AEC = (1/2)( arc AC + arc DB) = (1/2) (84 + 20) = (1/2) ( 104) = 52°
And angle AED is supplemental to angle AEC = 180 - 52 = 128°