MathDB
MMO 362 Moscow MO 1957 sequence of triangles in/circum-scribed in circle

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March 20, 2021
geometryanglesincirclecircumcirclesimilarsimilar triangles

Problem Statement

(a) A circle is inscribed in a triangle. The tangent points are the vertices of a second triangle in which another circle is inscribed. Its tangency points are the vertices of a third triangle. The angles of this triangle are identical to those of the first triangle. Find these angles.
(b) A circle is inscribed in a scalene triangle. The tangent points are vertices of another triangle, in which a circle is inscribed whose tangent points are vertices of a third triangle, in which a third circle is inscribed, etc. Prove that the resulting sequence does not contain a pair of similar triangles.