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VANDONGA10
1 năm trước
Cho hình chóp S.ABC đáy là ABC vuông cân tại B, SA vuông góc với (ABC) a) Chứng minh rằng các mặt bên của hình chóp là các tam giác vuông b) Kẻ đường cao AD của SAB và đường cao AE của SAC. Chứng minh rằng ADE vuông và SC vuông góc với DE.
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IX.Read the passage then do the tasks below. Hi! I am Nam. I’m twelve years old. I’m a student in grade 6, class 6A2. I live with my parents and my sister. We live in a small house in the country. This is my school. It is small and old but it is beautiful. In front of the school, there is a big yard. It is clean and there are many tall trees and beautiful flowers. In the afternoon, I often play soccer with my friends there. My school has fifteen classrooms and six hundred students. There are forty-three teachers in my school. They are good teachers. I love them and I love my school very much. a. Answer the questions. 1.Where does Nam live?  ………………………………………………………………………………………………. 2. Are there many tall trees and beautiful flowers in the school yard? …………………………………………………………….…………………………………. 3. How many teachers does his school have? ……………………………………………………………..…………………………………. b. Complete the sentences, using the information from the passage above. 4. ………………….…………………………….…………is small and old but it is beautiful. 5. In the afternoon, Nam often plays soccer with his friends in the ……..…………

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