user-avatar
745270246368605
2 năm trước
Cho tam giác ABC vuông tại A, AB=15cm, AC=20cm. Kẻ đường cao AH của tam giác ABC a. Chứng minh rằng AB^2= BH.BC, suy ra độ dài các đoạn thẳng BH và CH b. Kẻ HM vuông góc AB và HN vuông góc AC. Chứng minh rằng AM.AB=AN.AC, suy ra tam giác AMN đồng dạng tam giác ACB c. Tính tỉ số diện tích 2 tam giác AMN và ACB, suy ra diện tích tam giác AMN
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

VII.Read the following passage and mark the letter A, B, c, or D to indicate the correct word or phrase that best fits each of the numbered blanks. 23. A. calms down B. speeds up C. carries out D. puts off 24. A. popular B. liked C. widespread D. accepted 25. A. where B. after C. once D. when 26. A. preparation B. training C. guidance D. instruction 27. A. developing B. arranging C. planning D. designing Before people had electricity and gas, they cooked on wood and charcoal fires. A fairly recent addition to cooking is the microwave. This (23) _______the cooking time. Fan ovens are also more efficient. Barbecue cooking outside in the garden on a warm day in summer is very (24) _______. In the kitchen, utensils are used to contain the food, and they vary from open pans to pans with lids, frying pans, steamers, pressure cookers and woks. The kitchen is now the ‘hub’ of the house. The family, friends and visitors, (25) _______waiting for a meal to be prepared, all gather in the kitchen and help to prepare the dishes or watch others doing the cooking. The utensils available to aid the food (26) _______are plentiful. Different types of knives for example. Aprons and oven gloves help to protect us from spills and heat when taking hot dishes from the oven. Some people love cooking. (27) _______the meal, assembling the ingredients and then preparing the food. Others, however, prefer to open a tin of food and hot up the contents. III. Read the following passage and mark the letter A, B, c, or D to indicate the correct answer Pronouncing a language is a skill. Every normal person is an expert in the skill of pronouncing his own language; but few people are even moderately proficient at pronouncing foreign languages. There are many reasons for this, some obvious, some perhaps not so obvious. But I suggest that the fundamental reason why people in general do not speak foreign languages very well is that they fail to grasp the true nature of the problem of learning to pronounce, and consequently never set about tackling it in the right way. Too many people fail to realize that pronouncing a foreign language is a skill - one that needs careful training of a special kind, and one that cannot be acquired by just leaving it to take care of itself. I think even teachers of languages, while recognizing the importance of a good accent, tend to neglect, in their practical teaching, the branch of study concerned with speaking the language. So the first point I want to make is that English pronunciation must be taught; the teacher should be prepared to devote some of the lesson time to this, and should get the student to feel that here is a matter worthy of receiving his close attention. So, there should be occasions when other aspects of English, such as grammar or spelling, are allowed for the moment to take second place. 28. What does the writer actually say about pronouncing foreign languages? A. Only a few people are really proficient. B. No one is really an expert in the skill. C. There aren’t many people who are even fairly good. D. There are a lot of people who are moderately proficient. 29. The writer argues that going about the problem of pronunciation in the wrong way is_______. A. an obvious cause of not grasping the problem correctly B. a fundamental consequence of not speaking well C. a consequence of not grasping the problem correctly D. not an obvious cause of speaking poorly 30. The underlined word “one” in the passage refers to_______. A. skill B. careful training C. special kind D. itself 31.The best way of learning to speak a foreign language, he suggests, is by_______. A. picking it up naturally as a child B. learning from a native speaker C. not concentrating much on pronunciation D. taking on systematic work 32.The underlined word “aspects” in the passage probably means_______. A. pronunciations B. parts C. words D. sentences IX. Finish the second sentence so that it has a similar meaning to the first one. 33. It’s a pity that our teacher isn’t here at the moment. I wish_____________________. 34. It was such a good show that they decided to go and see it again. The show __________________. 35. He prefers typing to writing by hand. He’d rather__________________. 36. He speaks too quickly for me to understand. He doesn’t speak________________. X.Write new sentences as simitar as possible in meaning to the original sentences. 37. Could you lend me some money until the weekend? (from) 38. I can’t decide which hat I like more, the blue one or the green one. (choose) 39. I don’t think my English is good. I cannot join our English Speaking Club, (enough) 40. I don’t come from your country. I can’t understand your problems, (if) Giúp mình nhé,làm hết hộ cái!

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