MathDB
2023 Iran MO 2nd round P6

Source: 2023 Iran MO

May 17, 2023
geometry

Problem Statement

6. Circles W1W_{1} and W2W_{2} with equal radii are given. Let PP,QQ be the intersection of the circles. points BB and CC are on W1W_{1} and W2W_{2} such that they are inside W2W_{2} and W1W_{1} respectively. Points XX,YY \neq PP are on W1W_{1} and W2W_{2} respectively, such that BPQ=BYQ\angle{BPQ}=\angle{BYQ} and CPQ=CXQ\angle{CPQ}=\angle{CXQ}.Denote by SS as the other intersection of (YPB)(YPB) and (XPC)(XPC). Prove that QS,BC,XYQS,BC,XY are concurrent.