==See also==*Butterfly theorem*Cyclic polygon*Power of a point*Ptolemy's table of chords*Robbins pentagon==References====External links==*Derivation of Formula for the Area of Cyclic Quadrilateral*Incenters in Cyclic Quadrilateral at cut-the-knot*Four Concurrent Lines in a Cyclic Quadrilateral at cut-the-knot*Euler centre and maltitudes of cyclic quadrilateral at Dynamic Geometry Sketches, interactive dynamic geometry sketch.
*Derivation of Formula for the Area of Cyclic Quadrilateral*Incenters in Cyclic Quadrilateral at cut-the-knot*Four Concurrent Lines in a Cyclic Quadrilateral at cut-the-knot*Euler centre and maltitudes of cyclic quadrilateral at Dynamic Geometry Sketches, interactive dynamic geometry sketch.