Cho tam giác A B C có 3 góc nhọn, nội tiếp đường tròn tâm O . Các đường cao A D và C E của tam giác A B C cắt nhau tại H . Vẽ đường kính B M của đường tròn tâm O . 1. Chứng minh E H D B là tứ giác nội tiếp 2. Chứng minh tứ giác A H C M là hình bình hành 3. Cho góc ABC = 60*. Chứng minh B H = B O .

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Do you have a special hobby? Write an email (80-100 words) to your pen-friend, and tell him/her about it. You should base on the suggestions below: - What is your hobby? - When did you start it? - What do you do in your hobby? - Who do you like doing it with? - How much do you like doing it?/ How do you feel when you do it? - Why do you like doing it? - What will you do with your hobby in the future? Dear ........................, .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... .......................................................................................................................................... Love, ...........................(Your signature)