MathDB

10

Part of 1980 IMO Shortlist

Problems(1)

straight line D is tangent at A

Source: IMO 1980 Luxembourg, problem 4

5/6/2004
Two circles C1C_{1} and C2C_{2} are (externally or internally) tangent at a point PP. The straight line DD is tangent at AA to one of the circles and cuts the other circle at the points BB and CC. Prove that the straight line PAPA is an interior or exterior bisector of the angle ∠BPC\angle BPC.
geometrycircumcirclecirclesbisectorIMO Shortlist