Why always a circle tangent?

Author:
Terry Tam
Topic:
Circle
Point A is a center of the black circle passing through B. Choosing an arbitrary point C on the black circle as center, draw a green circle passing through B. Green circle intersects with the black circle at point D. Draw an orange circle with B as center passing through D. The orange circle intersects with the green circle at point E. Why line BE is always a tangent to the black circle?