MathDB
concurrency related to interior point of incircle connecting vertices

Source: China Northern MO 2011 p2 CNMO

October 28, 2022
geometryconcurrencyconcurrentincircle

Problem Statement

As shown in figure , the inscribed circle of ABCABC is intersects BCBC, CACA, ABAB at points DD, EE, FF, repectively, and PP is a point inside the inscribed circle. The line segments PAPA, PBPB and PCPC intersect respectively the inscribed circle at points XX, YY and ZZ. Prove that the three lines XDXD, YEYE and ZFZF have a common point. https://cdn.artofproblemsolving.com/attachments/e/9/bbfb0394b9db7aa5fb1e9a869134f0bca372c1.png