基础训练篇（24）
Ms. Mary was over eighty, but she still drove her old car like half her age. She loved driving very fast, and boasted of the fact 1. she had never, in her thirty-five years of driving, been punished 2. a driving mistake.
Then one day, she nearly lost her record. A police car followed her, and the policemen in it saw her pass a red light without 3. (stop).
When Ms. Mary came before the judge, he looked at her severely and said that she was too old to drive a car, and that the reason 4. she had not stopped at red light was most probably that her eyes had become weak 5 old age, so that she had simply not seen it.
When the judge had finished 6. he was saying, Ms. Mary opened the big handbag she was carrying and took out her sewing. Without saying a word, she 7. (choose) a needle with a very small eye, and threaded it at the first time.
When she had 8. (success) done this, she took the thread out of the needle again and handed both the needle and thread to the judge, saying, “Now it is your turn. I suppose you can drive a car well, and you have no doubts 9. your eyesight.”
The judge took the needle and tried to thread it. After half a dozen times, he had still not succeeded. The case against Ms. Mary 10. (dismiss), and her record remained unbroken.
的顶点
，
求：（1）
边上的中线所在的直线方程（2）
边上的高
所在的直线方程.
