olymmath

ISL 2019 G6

Let II be the incentre of acute-angled triangle ABCA B C. Let the incircle meet BC,CAB C, C A, and ABA B at D,ED, E, and FF, respectively. Let line EFE F intersect the circumcircle of the triangle at PP and QQ, such that FF lies between EE and PP. Prove that ∠DPA+∠AQD=∠QIP\angle D P A+\angle A Q D=\angle Q I P. (Slovakia)

Official text Transcription from NuminaMath olympiads, checked word for word against the official paper. Quoted with source.

Official text: IMO 2019 Shortlist booklet, page 10.

Solutions

Official solution Solution 1 by the IMO Problem Selection Committee

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