user-avatar
dodongchien98423
2 năm trước
*Cho tam giác ABC thoả mãn hệ thức b+c=2a. Trong các mệnh đề sau, mệnh đề nào đúng ? A. cosB+cosC=2cosA B. sinB+sinC=2sinA C.sinB+sinC=1/2 sinA D. sinB+cosC=2sinA *Cho tam giác ABC. Đẳng thức nào sai ? A. sin(A+B-2C)= sin3C B. cos (B+C)/2= sin A/2 C. sin(A+B)= sinC D. cos (A+B+2C)/2= sin C/2 *Gọi S= m^2a+m^2b+m^2c là tổng bình phương độ dài ba trung tuyến của tam giác ABC . Trong các mệnh đề sau mệnh đề nào đúng ? A. S=3/4 (a^2+b^2+c^2) B. a^2+b^2+c^2 C. S= 3/2( a^2+b^2+c^2) D. S= 3(a^2+b^2+c^2)
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

PRACTICE 3. Directions: Write the past participles of the verbs. The list contains both regular and irregular verbs. Simple Form Simple Past(PI) Past Participle (PII) Simple Form Simple Past Past Participle (PII) 1. bring Brought brought 14. play played played 2. build built built 15. read read* read 3. buy Bought bought 16. save saved saved 4. eat Ate eaten 17. send sent sent 5. plan Planned planned 18. speak spoke spoken 6. give gave given 19. spend spent spent 7. grow grew grown 20. take took taken 8. hit Hit hit 21. teach taught taught 9. hurt hurt hurt 22. go went gone 10. leave left left 23. visit visited visited 11. lose lost lost 24. wear wore worn 12. make made made 25. write wrote written 13. find found found 26. do did done PRACTICE 4. Directions: Use the given form of be (was, is, going to be, etc.) and complete the sentences with the past participles of any verbs in the list in Practice 3. 1. was There's no more candy. All the candy _____________ by the children. 2. is Arabic ______________ by the people of Syria and Iraq. 3. are Books ______________ by authors. 4. was My friend ______________ in an accident. He broke his nose. 5. is going to be Bombay, India, ______________ by thousands of tourists this year. 6. has been Wilr and Peace is a famous book. It _____was__ by millions of people. 7. will be The championship game ___will be___________in Milan next week. 8. can be Everyone ______________to read. I'll teach you if you'd like. 9. are going to be Our pictures ______________ by a professional photographer at the wedding. 10. have been Oranges ______________ by farmers in Jordan since ancient times. 11. is Special fire-resistant clothing ______________ by firefighters. 12. will be A new bridge across the White River ______________ by the city government next year.

1. He says he (come) __________________ here soon 2. He always (eat) _____________ a sandwich for breakfast 3. Why _________ you (leave) _________ the party early last night? 4. John and Mary (talk) _______________ on the phone now 5. My sister never (drink) _____________ coffee 6. He thinks he (be) ________________ rich someday 7. She (meet) ______________ her old friends tonight 8. The Robinsons (come) _____________ to Ha Noi in 2007 9. Tim (try) __________________ to improve his bad habits now 10. John and Susan (get) _____________________ married last year 11. I (see) _____________ in front of the bookstore last morning 12. He (study) _________________ about 2 hours every night 13. He (be) __________________ here five minutes ago 14. Look! the teacher (look) __________________ at you 15. I (visit) _________________ my grandfather yesterday 16. Hoa always (help) ___________ her parents doing the housework in her free time 17. Hoa (have) _____________________ breakfast with her parents now 18. You (have) ________________ a lot of new friends soon 19. English (be) _______________ the most popular language in the world 20. There (be) ________________ an interesting movie on TV last night 21. Bell (invent) __________________ the telephone in 1876 22. He (not eat) _________________________ anything every evening. 23. My mother (buy) ___________________ new clothes for Tet holiday next week 24. Listen! He (talk) _______________________ about you. 25. Yesterday, she (come) ____________________ to my house. 26. My mother __________________ a sick note for me yesterday. (write) 27. She never (stay) _______________ up late at night. 28. My mother (plant) _______________ flowers in the garden last Sunday. 29. Mozart (play) _______________ the piano when he (be) ______________ three. 30. I (brush) ____________ my teeth every night, but last night I (forget)______________ to brush them. 31. She needs (eat) _______________ a lot of vegetables and fruit. 32. He (not come) _______________ to the meeting last week. 33. My father never (take) _______________ medicine. 34. There (be) __________ nobody there when I (arrive) ______________ yesterday. 35. She never (stay) ____________ up late at night 36. Water (consist) ____ ___________ hydrogen and oxygen 37. They (live) ______ ________ in Hue 3 years ago 38. Please be quiet! I (try) _________________ to concentrate the lesson. 39. Hoa (invite) ____________ a lot of friends to her birthday party next week 40. Lan and I (see) ______________________ a movie tonight 41. They (buy) _________________ their house in 2005 42. He (go) ___________to school every day by bike, but yesterday he (go) ___________to school by bus 43. Minh usually (play) ______________ football after school 44. She (brush) ___________ her teeth every night, but last night she (forget)__________ to brush them 45. My mother (plant) _______________ flowers in the garden at the moment 46. Our class (have) _____________ a new English teacher next semester 47. My baby (sleep) _______________ at the moment 48. Tomorrow, my family (go) ______________ camping at Dam Sen park 49. It (rain) ___________________ heavily last night 50. He (need) ______________ a pen right now

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