olymmath

RU-ORAL-GEOMETRY 2015

Moscow Oral Geometry Olympiad 2015.

Other problems

Problem 1

In triangle ABCABC , the altitude AHAH passes through midpoint of the median BMBM . Prove that in the triangle BMCBMC also one of the altitudes passes through the midpoint of one of the medians.

Problem 2

The square ABCDABCD and the equilateral triangle MKLMKL are located as shown in the figure. Find the angle ∠PQD\angle PQD . Image

Problem 3

In triangle ABCABC , points D,ED, E , and FF are marked on sides AC,BCAC, BC , and ABAB respectively, so that AD=ABAD = AB , EC=DCEC = DC , BF=BEBF = BE . After that, they erased everything except points E,FE, F and DD . Reconstruct the triangle ABCABC (no study required).