user-avatar
84966096205
2 năm trước
Cho tam giác ABC có 3 góc nhọn (AB< AC). Kẻ đường cao CH. Trên tia đối của tia HC lấy điểm D sao cho HC = HD. a) Chứng minh ∆ AHC = ∆ AHD. b) Gọi M là trung điểm của AC; N là trung điểm của AD. Chứng minh tam giác ANM cân. c) Điểm E là giao điểm của CN và DM. Chứng minh 3 điểm A, E, H thẳng hàng.
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

Giúp mình với ạ! Mình cần gấp, cám ơn mng ạ ! 1.Read the text below and think of the word which best fits each space. Use only one word in each space. Write your answer in the numbered boxes. ADOLESCENT DEVELOPMENT While most parents worry about their children (1) ………well at school, what they often don’t realise is how many other changes are going on in their teenager. Humans are the only species that go through the teenage stage and, for many, it appears to be a waste (2) …………time. What does it achieve, after all? Yet evolutionary theory suggests (3) ……..phase of life must have come about for a reason. Until the child turns (4) ………….a teenager, they are deeply sensitive to the world around them. They instinctively want to take (5) …………of children younger than themselves and they dislike seeing others in pain. The brain of teenager has lots all this sensitivity. It is focused (6) ……….itself and on very simple questions, such as: Do I belong here? Is that person a (7) ……..friend or just pretending to be one? The parental complaint of the insensitive teenager is far (8) ……….fiction. Evolutionary biologists are just starting to study the adolescent brain, so there are no firm answers. But if you asked one of them to make (9) ………guess, they would probably point to the early years of human development, which humans spent in small groups, constantly on the move. In those days, the unity of the group was of vital importance. The young (10) ……………to show complete devotion to that, or the group’s survival was at risk. 2.Write the correct FORM of each bracketed word in the numbered boxes WORKERLESS FACTORIES The factory production line allowed (1. manufacture) ….……..to break the production process down into a series of small (2. complicate) ………..tasks, each of which could be easily learned and carried out in a different part of the factory. These improvements on the (3. assemble) .………. line led to massive increases in productivity. From the very beginning, (4. machine) ….…was a fundamental part of this: the (5. convey) ………belt, the forklift truck, packaging machines. Each time a new invention came along, it was time to reconsider the whole process. As the science of (6. robot) ……….….has advanced, robots have gradually displaced humans in the more mundane, (7. repeat) ………..jobs on the factory floor: packing, stacking, painting, joining and so on. In fact, the final goal of a fully automated and (8. computer) …..…… factory has already been achieved in some areas. In Texas, for example, a (9. window) …..……..., lightless, workless IBM plant turns out keyboards 24/7, with only a few technicians carrying out the repairs and (10. maintain) ………….needed to keep the place running smoothly. 3.Complete the following sentences with correct prepositions / particles. Write your answer in the numbered boxes. 1. A number of problems came ________ in the meeting yesterday. 2. The thieves managed to make ________ with all the company’s electronic files. 3. Quick! Put ________ that match before we burn the house down. 4. The little boy complained about that he was always being blame ________ everything. 5. The situation is getting ________ control; we must take action immediately. 6. ________ my surprise, he won the competition. 7. The new safety measures are still _________discussion. 8. This parcel must be posted _________ delay. 9. His lack of punctuality resulted __________his dismissal from work. 10. Could you turn___________ the air conditioner? It’s hot here. 4.: Finish each of the sentences in such a way that it means exactly the same as the sentence printed before it 1. Her behaviour tends to be bad when she is under pressure. She has……………………………………………………………………………………….. 2.The clinic had such a lot of clients that it had to move to bigger premises. The clinic had …………………………………………………………….…………………. 3.The discussion group formed back in May. May …………………………………………………………………………………………. 4. Immediately he had learnt about his mother’s incurable disease, he cried his eyes out. No sooner................................................................................................................................. 5.You don’t listen and that’s why you make so many mistakes. If only you …………………………………………………………….…………………….. …………………. THE END ......................

Đề bài : Đọc đoạn văn và trả lời câu hỏi Champa is a sun bear . She is 12 years old . Bears usually live in the forest but Champa lives in the bear center at Cat Tien National Park . The bear center has a swimming pool , climbing towers , and comfortable places for Champa to sleep , eat , and play . Some of Champa's family members live there with her . There are some trees in the bear center and Champa loves to climb to the top of them . Champa has big teeth but she mainly eats fruit . Champa's favorite food is mangoes , but she also eats apples , nuts , eggs , and honey . The park keepers bring Champa and her family fruit to cat every day . Sun bears usually sleep during the day and wake up at night . Champa likes the park keepers and wakes up when she hears them bringing food in the evenings . 1. How old is Champa ? 2. Where do bears usually live ? 3. Where does Champa live ? 4. What does the bear center have ? 5. Who lives with Champa ?

2018 © Loga - Không Ngừng Sáng Tạo - Bùng Cháy Đam Mê
Loga Team