MathDB

320

Part of 1956 Moscow Mathematical Olympiad

Problems(1)

MMO 320 Moscow MO 1956 triangles ABC,BCD,CDA,DAB not all acute

Source:

8/19/2019
Prove that there are no four points A,B,C,DA, B, C, D on a plane such that all triangles △ABC,△BCD,△CDA,△DAB\vartriangle ABC,\vartriangle BCD, \vartriangle CDA, \vartriangle DAB are acute ones.
acutegeometryangles