Circle Theorem 2
1. Angles at the circumference subtended by arcs of the same length are equal.
2. The size of an angle at the circumference subtended by an arc is proportional to the arc length.
The arc length of BG is equal to the arc length of ED. You may adjust the point F and C to determine the value of them. Is it still the same angle?
The arc length of ED is double the arc length of ED. You may adjust the point F and C to determine the value of them. Is the angle value of F still double of the angle value of C?