MathDB
2015-2016 Fall OMO #16

Source:

November 18, 2015
Online Math Open

Problem Statement

Given a (nondegenrate) triangle ABCABC with positive integer angles (in degrees), construct squares BCD1D2,ACE1E2BCD_1D_2, ACE_1E_2 outside the triangle. Given that D1,D2,E1,E2D_1, D_2, E_1, E_2 all lie on a circle, how many ordered triples (∠A,∠B,∠C)(\angle A, \angle B, \angle C) are possible?
Proposed by Yang Liu
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