olymmath

RU-ORAL-GEOMETRY 2013

Moscow Oral Geometry Olympiad 2013.

Other problems

Problem 1

In triangle ABCABC the angle bisector AKAK is perpendicular on the median is CLCL . Prove that in the triangle BKLBKL also one of angle bisectors are perpendicular to one of the medians.

Problem 2

With a compass and a ruler, split a triangle into two smaller triangles with the same sum of squares of sides.

Problem 3

The bisectors AA1AA_1 and CC1CC_1 of the right triangle ABCABC ( ∠B=90o\angle B = 90^o ) intersect at point II . The line passing through the point C1C_1 and perpendicular on the line AA1AA_1 intersects the line that passes through A1A_1 and is perpendicular on CC1CC_1 , at the point KK . Prove that the midpoint of the segment KIKI lies on segment ACAC .