Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
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# Problem A. 632. (January 2015)

A. 632. Let $\displaystyle ABCD$ be a convex quadrilateral. In the triangle $\displaystyle ABC$ let $\displaystyle I$ and $\displaystyle J$ be the incenter and the excenter opposite to vertex $\displaystyle A$, respectively. In the triangle $\displaystyle ACD$ let $\displaystyle K$ and $\displaystyle L$ be the incenter and the excenter opposite to vertex $\displaystyle A$, respectively. Show that the lines $\displaystyle IL$ and $\displaystyle JK$, and the bisector of the angle $\displaystyle BCD$ are concurrent.

Russian problem

(5 pont)

Deadline expired on February 10, 2015.

### Statistics:

 5 students sent a solution. 5 points: Fehér Zsombor, Janzer Barnabás, Nagy-György Pál, Saranesh Prembabu, Williams Kada.

Problems in Mathematics of KöMaL, January 2015