[size=100][size=150]The size of the [b]angle[/b] at the[b] centre of a circle [/b]subtended by the same arc is [b]twice[/b] the size of the angle at the [b]circumference[/b].[/size][/size][br][size=150] [br]1. Adjust the point E to determine the angle value of point A.[br]2. Adjust the point C or D to determine the angle value of point E.[/size]