Geometry · Incircle · Tangent lengths · Midline · Angle bisector · Concurrency

Problem 4, 2017

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NationalProof

Let \(ABC\) be a triangle. Prove that the following three lines all pass through one point:

the bisector of the angle at \(A\); the line through the midpoints of the sides \(CA\) and \(CB\); and the line through the two points at which the incircle of the triangle touches the sides \(AB\) and \(BC\).

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Serbian National Competition (Drzavno takmicenje) 2017, high school grade I, category A, problem 4. Organized by the Mathematical Society of Serbia (DMS). Source