In acute triangle △ABC, ∠A>∠B>∠C. △AC1B and △CB1A are isosceles triangles such that △AC1B∼+△CB1A. Let lines BB1,CC1 intersects at T. Prove that if all points mentioned above are distinct, ∠ATC isn't a right angle. Kiepert Hyperbolageometryconics2024 CTST