Secants Intersecting Inside the Circle
by Sofia Arcoy
Interact with Points B, C, D, and E to observe the relationship of Arcs DC and BE and the angles they form: Angles DFC and BFE.
In this secant-secant relationship, since they intersect inside the circle, they form two angles, each intercepting either of the arcs. You should have observed that one-half of the sum of Arcs DC and BE is equal to the angles they make, Angles DFE and BFE.