Garfunkel's inequality - Minh Ha Nguyen and Nikolaos Dergiades Let I be the incenter of triangle ABC and U, V, W the intersections of the segments IA, IB, IC with the incircle. If the centroid G is inside the incircle, and D, E, F the intersections of the segments GA, GB, GC with the incircle. Jack Garfunkel [Crux Mathematicorum, Problem 648] asked for a proof that the perimeter of UVW is not greater than that of DEF. This problem is hitherto unsolved. We give a proof in this note. ✪ ✪ ✪ ✪ ✪ Link tải tài liệu: LINK TẢI TÀI LIỆU Theo LTTK Education