A：
B：
C：
D：
① How tall is it? ____ A. Zhang Yong.
② Who is the tallest boy? ____ B. Maybe 5 metres.
③ What size are your shoes?____ C. Forty yuan.
④ How much is your T-shirt? ____ D. Size 38
⑤ How old are you?____ E. I'm fifteen years old.
，顶点
，该三角形的内切圆方程为（ ）
