5 congruent triangles inside convex 5gon (2023 Novosibirsk Oral Geo Oly 7.4)
Source:
September 4, 2023
geometrycongruent trianglespentagoncongruence
Problem Statement
Inside the convex pentagon , a point was chosen, and it turned out that all five triangles , , , and are congrunet to each other. Prove that these triangles are isosceles or right-angled.