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2 lines meet on the altitude

Source: Sharygin Geometry Olympiad Correspondence Round 2017 P-9 (Grade-8-9)

May 1, 2017

geometry

Problem Statement

Let

C_0

be the midpoint of hypotenuse

AB

of triangle

ABC

;

AA_1, BB_1

the bisectors of this triangle;

I

its incenter. Prove that the lines

C_0I

and

A_1B_1

meet on the altitude from

C

. Proposed by A.Zaslavsky