user-avatar
dunghoang.vvt
2 năm trước
Cho hình vuông ABCD có cạnh bằng a. một đường thẳng d đi qua tâm O của hình vuông cắt AD, BC tại E, F. Từ E, vẽ đường thẳng song song với BD. từ F, vẽ đường thẳng song song với AC, hai đường thẳng này cắt nhau tại I. a, Chứng minh 3 điểm A, I, B thẳng hàng. b, Kẻ IH vuông góc với EF. Chứng minh H thuộc một đường tròn cố định khi đường thẳng d quay quanh O. c, Đường thẳng IH cắt trung trực của AB tại K. Chứng minh rằng: tứ giác AKBH nội tiếp. Từ đó suy ra K cố định. d, Tìm vị trí của d để diện tích tứ giác AKBH lớn nhất. HELP
Thích Trả lời Chia sẻ

Các câu hỏi liên quan

I. Fill in each gap with a suitable prepositions: 1. That village is well-known ___ carving eggshells. 2. He was very rude ___ children. 3. His is ___ stress but he needs a little stress in his life. 4. Some English words but he needs a little stress in his life. 5. The station platform was crowded ___ people waiting ___ the train. 6. There is a decrease ___ the supply ___ that good. 7. Are you disappointed ___ your study at school? 8. All the streets in my village are ___ bad condition. 9. Mark decied to give ___ sports because he wanted to concentrate ___ his studies. 10. She is very short ___ money. 11. Do you spend much money ___ clothes? 12. He met her on the street ___ chance. II. Fill in each gap in the passage with one suitable sentence A - G: How can we keep our teeth health? Firstly, we ought to visit our dentist twice a year. He can (1) ___ before they destroy the teeth. He can examine our teeth to check that they are growing in the right way. Unfortunately, many people (2) ___ before they see a dentist. Secondly, we should brush our teeth with a toothbrush and fluoride toothpaste at least twice a day - once after breakfast, and once before (3) ___. We can also use wooden toothpicks to clean between our teeth after meal. Finally, we should (4) ___ : milk, cheese, fish, brown bread, potatoes, red rice, raw vegetables and fresh fruit. Chocolate, sweets, biscuits and cakes are bad, especially when we (5) ___. They are harmful because they stick to our teeth and cause decay. A. we go to bed B. eat food that is good for our teeth and our body C. look after our teeth D. eat them between meals E. fill the small holes in our teeth F. wait until they have a toothace G. thwy hurt my teeth

IV. Write the correct form of tense of the verbs in brackets 1. Glastonbury festival____________ ( organise) every year in the village of Pilton, England 2. In 1076, King Ly Nhan Tong__________( build) the Imperial Academy as the first university of Vietnam 3. The first temples of My Son Sanctuary_________( make) of wood in the 4th century 4. An altar to Chu Van An__________( set) up in the Temple of Literature 5. We___________( not do) any practice tests yet so I’m not sure what they ‘ re like 6. Wait a minute he_________( speak) to someone on his mobile 7. Many different languages __________ ( speak) in Canada 8. The Imperial City of Hue can _________ ( divide) into two main parts 9. You’d better __________ (rent) a bike if you want to travel around 10. I don’t want to go to Huong Pagoda. How about ______ (visit) Ho Chi Minh Mausoleum?

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