To find angles of the triangle
Source: Sharygin Geometry Olympiad Correspondence Round 2017 P-4 (Grade-8)
May 1, 2017
geometry
Problem Statement
A triangle is given. Let C\ensuremath{'} be the vertex of an isosceles triangle ABC\ensuremath{'} with \angle C\ensuremath{'} = 120^{\circ} constructed on the other side of than , and B\ensuremath{'} be the vertex of an equilateral triangle ACB\ensuremath{'} constructed on the same side of as . Let be the midpoint of BB\ensuremath{'}
Find the angles of triangle KCC\ensuremath{'}.
Proposed by A.Zaslavsky