Problem 3 (Geometry) was noted for its "attackability" through multiple different methods, including classic Euclidean geometry, vectors, and coordinate geometry.
A problem involving an acute triangle and perpendicular lines from a midpoint. The goal was to prove an equality between two angles, Comentarii JBMO 2015
Problem 1 was criticized for being perhaps too simple for an international olympiad, acting more as a "points booster" than a differentiator for top talent. Problem 3 (Geometry) was noted for its "attackability"
. Notes indicate that many participants were able to solve this using analytical or vector methods. including classic Euclidean geometry