Problem

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Tags: ratio, geometry, cyclic quadrilateral, geometry unsolved



Let γ,Γ be two concentric circles with radii r,R with r<R. Let ABCD be a cyclic quadrilateral inscribed in γ. If AB denotes the Ray starting from A and extending indefinitely in Bs direction then Let AB,BC,CD,DA meet Γ at the points C1,D1,A1,B1 respectively. Prove that [A1B1C1D1][ABCD]R2r2 where [.] denotes area.