MathDB
BC //MN wanted, 3 angles 45^o, projections (2013 Kyiv City MO Round2 8.3)

Source:

August 5, 2020
geometryanglesequal anglesparallel

Problem Statement

Inside ∠BAC=45∘\angle BAC = 45 {} ^ \circ the point PP is selected that the conditions ∠APB=∠APC=45∘\angle APB = \angle APC = 45 {} ^ \circ are fulfilled. Let the points MM and NN be the projections of the point PP on the lines ABAB and ACAC, respectively. Prove that BC∥MNBC\parallel MN .
(Serdyuk Nazar)
Back to ProblemsView on AoPS