# Products Determined by a Point on the Circumcircle

Products Determined by a Point on the Circumcircle

Let ABC be a triangle and P be a point on the circumcircle of circumradius . Let A' and B' be the perpendicular projections of P onto BC and CA, respectively. Let Q be the perpendicular projection of P onto A'B'. Then .

R

PA×PA'=2×PQ

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