Triangle Inequality

He was a math teacher who spent his life teaching triangle inequalities: the sum of two sides is greater than the third side. He and his wife and their children, about three of them, lived in the same town and knew each other. When his wife fell ill, the children came to deliver medicine every day, and he boiled the medicine every day. I think this is the most beautiful angle in the world. Before his death, his wife held their hands and said: "You are my two sides, and together they are longer than life." After she left, he played chess with the children every day and never mentioned her. Someone asked them if they were sad. He said: "The triangle inequality is a problem that cannot be solved in this life."