Cho tam giác ABC nhọn (AB < AC) nội tiếp trong đường tròn (O). Các đường cao AD, BE, CF cắt nhau tại H. Tia EF cắt tia CB tại K. a) Chứng minh tứ giác BFEC nội tiếp và KF.KE = KB.KC b) Đường thẳng KA cắt (O) tại M. Chứng minh tứ giác AEFM nội tiếp. giúp em ạ.em cần gấp

Lan went to school after saying goodbye to her parents. > After Lan ................................................................................ The family becomes a source of encouragement in times of personal success or defeat. We are conscious of that. >We are consious............................................................................................................................... He was so brave that he ran after the thief to get the bag back >It was...................................................................................................................................................... Each family needs its own special set of rules and guidelines. It is sure about that. >It is sure...................................................................................................................................................

Câu 1 : Hòa tan đồng (II) hiđroxit vào HCl tạo thành 1,8 g nước tính khối lượng của các chất phản ứng Câu 2: cho natri vào HCl tạo thành 4,481 khí tính khối lượng natri

Vẽ vương miện Mikimoto của Miss Universe (Hoa hậu hoàn vũ)

Many people had been homeless before they were rescued by the volunteers. A.After they were rescued by the volunteers, many people had been homeless. B.After they had been rescued by the volunteers, many people were homeless. C.After they had been rescued by the volunteers, many people weren’t homeless. D.After they were rescued by the volunteers, many people hadn’t been homeless.

bn nào giỏi sinh 9. Giúp mk vs ạ

Một thửa ruộng hình chữ nhật có chu vi dài 280 m chiều rộng bằng 3/4 chiều dài người ta đem trồng lúa trên thửa ruộng đó cứ 100 mét vuông thu được 62 kg thóc A,Tính chiều dài và chiều rộng của thửa ruộng B. Mọi người ta đã thu hoạch được bao nhiêu tạ thóc trên thửa ruộng đó C, người ta lấy 50% số thóc đó đem bán lấy tiền dễ chi tiêu giá tiền một kg thóc là 3000₫ tính số tiền thóc bán được Tìm số tự nhiên có 6 chữ số biết chữ số ở hàng đơn vị là 4 Nếu chuyển chữ số hàng đơn vị lên đầu thì được số mới gấp lần 4 số cũ

Dòng chảy đều trong cống tròn có đường kính D = 2.2m, tải một lưu lượng là Q = 4m/s. Biết cống có độ nhám n = 0.016, độ dốc đáy cống i = 0.0008. Hãy xác định độ sâu mực nước h (m) trong cống? ai giúp em với ạ câu này với ạ em cần gấp

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Fill in the blank with “for” or “since”. 1. It has been raining ...................... lunchtime. 2. My boss will go away ...................... the next ten days. 3. I’m staying in England ...................... a year. 4. She has lived in London ...................... 1985. 5. Please hurry up! We have been waiting ...................... an hour. 6. I have known her ...................... January. 7. Nam’s father has worked in this company ...................... 20 years. 8. Have you learned English ...................... a long time? 9. I haven’t seen Tom ...................... we left school. 10. The house is very dirty. We haven’t cleaned it ...................... years. 11. My sister has been a student ...................... two years. 12. We’ve lived here ...................... 1990. 13. I haven’t seen Linh ...................... my birthday party. 14. She has been away ...................... a year. 15. We’ve already waited ...................... five days. 16. They haven’t had any rain ...................... very long time. 17. That building has been there ...................... the 19th century. 18. I have known them ...................... many years. 19. They have only been there ...................... a few minutes. 20. My brother works for a company called FPT. He has worked for them ...................... he graduated from university. Put the verbs in brackets in the present perfect or the simple past tense. 1. I ...................... (do) all the housework. The flat is really clean now. 2. He ...................... (write) a novel for two years, but he ................................. (not finish) it yet. 3. My brother ...................... (leave) home 10 years ago. I ................................. (never/ meet) him again since then. 4. I like your car. How long ...................... you ...................... (have) it? 5. What ...................... you ...................... (do) last weekend? ...................... (play) golf? 6. Mai ...................... (buy) a new dress last week, but she ...................... (not wear) it yet. 7. Mr. Quang ...................... (teach) Math in this school since he ...................... (graduate) from the university in 1989. 8. ...................... you ...................... (hear) of Agatha Christie? She ...................... ( be) a novels writer. You ...................... (read) any of them 9. When I ..................... (get) home last night, I ..................... (be) very tired and I ...................... (go) straight to bed. 10. Daniel ...................... (earn) some money last week. But I’m afraid he ..................................... (already/ spend) it all. Put the verbs in brackets in the present perfect or the simple past tense. 1. We (never watch) that TV programme. 2. We (watch) a good programme on TV last night. 3. He (read) that novel many times before. 4. He (read) that novel again during my last vacation. 5. I (have) a little trouble with my car last week. 6. However, I (have) no trouble with my car since then. 7. I (not see) John for a long time. I (see) him 3 weeks ago. 8. The school bell (ring) . We must go now. 9. I (meet) Mary last night. She (become) a very big girl. 10. He is very thirsty. He (not drink) since this morning. Give the correct form of the verbs in the present perfect. 1. Tom (see) this film before. 2. I (finish) my exercise already. 3. They (live) here since 1990.