(二) 根据短文内容， 回答下列问题。
I'm Tony. I'm a boy. I live in a big house with my family. I have a sister and a brother. My sister likes to draw pictures and sing. My brother likes to play football. We all go to school by bus. My mother works in a hospital. She is a doctor. My father has a farm. The farm is very big. We like to go for a walk together. I love my family.
，顶点
，该三角形的内切圆方程为（ ）