The incircle of the triangle ABC touches the sides BC,CA and AB at D,E and F respectively. Let the circle ω touch the segments CA and AB at Q and R respectively, and the points M and N are selected on the segments AB and AC respectively, so that the segments CM and BN touch ω. The bisectors of ∠NBC and ∠MCB intersect the segments DE and DF at K and L respectively. Prove that the lines RK and QL intersect on ω.Proposed by Tran Quang Hung geometryincircleconcurrency