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An interesting Function on the space of quadrilaterals

Drag the large BLACK dots {A, B, C, D} to form a quadrilateral you are interested in. This environment constructs a function, [call it Q], from the space of quadrilaterals to the space of quadrilaterals as follows - --circumscribes a circle around points A,B,C with center at E --circumscribes a circle around points B,C,D with center at F --circumscribes a circle around points C,D,A with center at G --circumscribes a circle around points D,A,B with center at H and then constructs the quadrilateral EFGH (in GREEN) Explore this function - what is the domain of Q ? the range of Q ? Conjectures ? Proofs ? Extensions ? Challenge - How cyclic is my quadrilateral ? Given a collection of n-sided polygons - some cyclic, others not - can you devise a measure of "cyclicity" - that is, a way of ordering them from "least cyclic" to cyclic ?

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