Angle of the arc of the circle is the angle whose vertices are on the circle and the two arms of the angle passing through both ends of the diameter line.
The angle in the arc of a circle is the angle whose vertex angles are on the circle and the two arms of the angle through both the end of one line diameter.
corner of arch of the Circle is a corner point of the corner on circle and angle of both arms through the two ends of the line through the center of the line