In the diagram below, BA and BC are tangents to the circle at points A and CC respectively. If angle AEC = 110 degrees and angle DCE = 80 degrees, find angle ABC.
Note that arc ADC = 2*measure of angle AEC = 2*110 = 220°
So angle ADC intercepts arc AEC = 360 - 220 = 140°
So we have this relationship :
x = (1/2) (arc ADC - arc AEC) = (1/2) ( 220 - 140) = (1/2)(80) = 40°
