r2069

Let P, Q be two isogonal points; Pa, Qa their cevian traces in BC. Let Apb, Apc the ninecenters of APaB, APaC, and Aqb, Aqc the ninecenters of AQaB, AQaC. The points Apb, Apc, Aqb, Aqc are concyclic.


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