sin(180-a)=sin a
cos(180-a)=-cos a
đó là công thức lượng giác bình thường nha bạn
sin(180-a)= sin a
cos(180-a)= -cos a
Cái này có trong sgk toán nhé
Một ổ dịch uống gà H5N1 lây lan đều về mọi phía và chỉ lây trong phạm vi diện tích : 28260000m2. Hỏi gà của vùng dân cách ổ dịch 3,2km có bị lây nhiễm bởi ổ dịch không ? Tại sao ?
Thuyết minh về một gương mặt thể thao Nguyễn Thị Ánh Viên
Cho tam giác ABC góc A bằng 60 độ , R bằng 5 phần căn 3 , r bằng căn 3 . Tính C và S của tam giác.
Một sợi dây thép dài 6,28m. Người ta uốn thành một vòng tròn rồi đặt lên sàn nhà. Tính diện tích phần sàn nhà nằm trong vòng tròn.
Cho hình thang ABCD có đáy lớn CD . Kẻ AE // BC ( E thuộc đường chéo BD ) và BF // AD ( F thuộc đường chéo AC ) . CM rằng : a, AE/BC = AO/OC và BF/AD = BO/OD b, AE.AD =BF.BC c, EF // CD d, AB mũ 2 = CD.EF Giúp mình với
V. Give the correct form of the word in brackets to complete each sentence . (10 pts) 26. ______ has caused many so-called man-made disasters. (forest) 27. _____ often walk through the streets shouting or singing about something they sell. (cry) 28. Gas and oil _________________ always increases in cold weather. (consume) 29. The police are interested in the sudden _________________ of the valuable painting. (appear) 30. He claimed that his ____________________ had caused him to become a criminal. (bring up) 31. A lot of toys encourage children’s_______________. (imagine) 32. The factory has provided cheaper_______________ lately. (produce) 33. Burning coal is an__________ way of heating a house. Gas is much cheaper. (economy) 34. According to some scientists the earth is losing its outer atmosphere because of _____. (pollute) 35. She has one of the biggest art ________________________ in Britain. (collect) VI. Match a beginning in column A with the most suitable ending in column B . (5 pts) A B 36. I must get back to work, a. That’s right, I am 37. Hello. You must be Maryam. b. which is the capital city of California. 38. Andrew is flying to Sacramento, c. we will have no fresh water to use. 39. Do you know that you can only live without water for four days? d. otherwise I’ll get the sack. 40. If we pollute the water, e. It depends on where you are and what you are doing, surely? VII. Choose the underlined part of each sentence that needs correcting . (5 pts) 41. Preserving natural resources mean reserving them for our future. A B C D 42. Despite of the increase in air fares, most people still prefer to travel by plane. A B C D 43. Regardless of your teaching method, the objective of any conversation class should be for students to practice speaking words 44. The injured man was taken to the hospital . A B C D 45. In order for one to achieve the desired results in this experiment, it is necessary that he work as fastly as possible. A B C D VIII. Read the text below the fill in the missing words . (15 pts) SAVING THE TIGER In 1973, when the tiger appeared to (0) be facing extinction, the World Wide Fund for Nature and (46) _____Indian Government agreed to set (47) ______ “Operation Tiger”- a campaign (48) ______ save this threatened creature. They started by creating nine special parks (49) _____that tigers could live in safety. The first was at Ranthambhore, a region (50) _____ was quickly turning into a desert (51) _____ too much of the grass was being eaten by the local people’s cattle. At the time there (52) ______ just fourteen tigers left there. The government had to clear twelve small villages, which mean moving nearly 1,000 people and 10,000 cattle so the land (53) ______ be handed back to nature. Today, Ranthambhore is a very different place, with grass tall (54) _____ for tigers to hide in, and there are now at (55) ______ forty of them (56) _____ the park, wandering freely about. Other animals have also benefited. For example, there are many (57) _____ deer and monkeys than before. The people (58) _______were moved are now living in better conditions. They live in new villages away (59) _____ the tiger park, with schools, temples and fresh water supplies. There are now sixteen such tiger parks in India and the animals’ future looks (60) ______little safer.
Cho tam giác ABC . Từ điểm D thuộc cạnh BC kẻ DE // BC ( E thuộc AC ) . Nối BE cắt CD tại O . Kéo dài AO cắt DE , BC lần lượt tại K , M . CM rằng a, DK/BM = KE/MC b, DK/MC=OK/OM=KE/BM c, DK = KE và MC = MB
Đ ề 4 I. Choose the word (A, B, C, or D) which has the underlined part pronounced differently . (5 pts) 1. A. cl i mate B. com i c C. h i ke D. webs i te 2. A. work ed B. laugh ed C. hop ed D. nak ed 3. A. c over B. c ategory C. an c ient D. de c orate 4. A. er u pt B. h u mor C. U FO D. comm u nicate 5. A. B uddhism B. bom b C. via b le D. bul b II. Choose the word (A, B, C, or D) which has the stress pattern different from others . (5 pts) 6. A. comprise B. depend C. design D. novel 7. A. tropical B. collection C. tendency D. charity 8. A. friendliness B. occasion C. pagoda D. deposit 9. A. importing B. specific C. impolite D. important 10. A. federation B. unpolluted C. disappearing D. profitable III. Choose the best answer to complete each sentence . (10 pts) 11. All the sentences below use “the”, which one is correct? A. Can you pass the sugar please? B. The crime is a problem in many big cities. C. The apples are good for you. D. I love the skiing. 12. Our friends have lived in Ho Chi Minh city __________ 2002 A. for B. since C. in D. about 13. He prefers soccer ___________ tennis A. from B. than C. to D. or 14. If they worked more carefully, they ___________ so many mistakes. A. won’t make B. don’t make C. wouldn’t make D. didn’t make 15. He __________ to his friend’s party when his parents asked him to go home. A. goes B. was going C. went D. has gone 16. There’s a strange man behind us. I think_______. A. we are followed B. we are being followed C. we are being following D. we are following 17. Which of the following is the strongest advice? A. You should get a hair-cut. B. If I were you I’d get a hair-cut. C. You ought to get a hair-cut. D. You really must get a hair-cut. 18. ________ you mind if I use your dictionary? A. Will B. Do C. Can D. Did 19. Mr. Vo Van Kiet, ______ was our former Prime Minister, was born in Vinh Long. A. that B. whose C. who D. whom 20. All that rubbish will have to be _____ at once. A. get rid of B. got rid of C. got rid D. getting rid of IV. Give the correct form of the verbs in the brackets to complete the passage : (10 pts) 21. My friend was (make) ____________ (pay) ______________ back the book. 22. Hardly he (take) ____________ up the book when the phone (ring) ________. 23. Can you imagine what I (come) ___________ across when I (roll) __________ up the carpet yesterday? 24. If she wins the prize, it (be) _________________ because she (write) _____________ very well. 25. He resented (ask) _________ (wait) __________. He had expected the minister to see him at once
Toán hình 7 Cho ΔABC có 3 góc nhọn, AB < AC < BC. Các tia phân giác của góc A và góc C cắt nhau tại O. Từ O kẻ OF ⊥ BC, từ O kẻ OH ⊥ AC. Lấy điểm I trên đoạn FC sao cho FI = AH. Gọi K là giao điểm của FH và AI a. Chứng minh ΔFCH cân b. Chứng minh AK = KI c. Chứng minh 3 điểm B, O, K thẳng hàng
Mọi người cho em hỏi bài toán tính lim cái khúc bấm máy giải ptr bậc 2 lấy nghiệm là khi ra nghiệm rr mình dùng công thức a(x-x1)(x-x2) hay (x-x1)(x-x2) ạ ? Tại em làm 1 bài theo 2 công thức đó luôn mà lại ra 2 kết quả khác nhau nên em kh biết cái nào đúng ạ ?
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