Cho ΔABC có AB=AC=5cm, BC=8cm. Kẻ AH ⊥ BC (H ∈ BC). Chứng minh:. a)HB=HC và góc BAH= góc CAH b)Tính AH c)Gọi D và E là chân đường vuông góc kẻ từ H đến AB và AC. Chứng minh ΔHDE cân Cho mình xin hình đầy đủ nha, mình cảm ơn nhiều

phần vận dụng ạ ghi rõ mở thân kết ạ

Giải hộ mình bài 2 3 vs ạ cảm ơn nha

diện tính bảng lớp em khoảng :A. 2 cm2 B .2 dm2 C .2 m2 D. 2 km2

I. Read the following text and choose the best answer for the questions below. Almost all our energy comes from oil, coal, and natural gas. We call them fossil fuels. The earth's fossil fuels are running out. What will happen when there is no oil, coal and gas on the earth?Scientists are trying to find and use other alternative sources of energy. We can use energy from the sun, the wind, and the water.Solar energy is unlimited. The sun supplies all the energy used to grow plants, to evaporate water for rain, and to maintain the temperature of the planet. All are necessary for human life. If we are able to collect solar energy, we will be sure to have this abundant source of power. 1. What are the other words or phrase for fossil fuels? A. oil B. natural gas C. oil, gas, natural gas D. coal 2. Natural sources of energy are energy from ________. A. wind B. the sun, wind, water C. water D. the sun 3. From which do plants on the earth get energy? 1 điểm A. the sun B. the Mars C. the moon D. stars 4. We are asking the question, "What will happen when there is no oil, coal, and gas on the earth?" because ________. A. we are now depending so much on oil, coal, and natural gas B. other sources of energy can come from the sun, wind, and water C. we are looking forward to seeing great changes D. we are looking for other alternative sources of energy 5. The word "abundant" in the passage is closest in meaning with ________. A. limited B. natural C. plentiful D. necessary II. Choose true or false Linh and her friends went camping for four days in Da Lat. They left their house at 6 o'clock. Ha brought a tent and some foods. Tom brought a ball to play volleyball. Ly brought her camera to take some photos. Nga and Mai brought some drinks. They took some orange juice. They didn't take iced tea because it was cold. They also took some food. Their favorite foods are chicken, lettuces and tomatoes. Ha's mother helped them to arrange food and drink for their camping. They stayed in a small hotel. The hotel looked over a very beautiful garden with a lot of flowers and green trees. They enjoyed the fresh air there. Linh said her dream house was one surrounded by a flower fence. 6. Linh and her friends went for a camp for four days. A. True B. False 7. They went to Da Lat at 6 o'clock. A. False B. True 8. Nga brought a basket to play volleyball. A. False B. True 9. Nga and Mai didn't take iced tea because it was cool. A. False B. True 10. Ha's mother helped them to arrange food and drink. A. True B. False

Cho phương trình x2 -2(m-1)x+m2 -3=0 (x là ẩn, m là tham số) a) Định m để phương trình có hai nghiệm phân biệt. b) Gọi x1 và x2 là các nghiệm của phương trình. Tìm m để x12 +x22 =4

Cho (o), dây bc .các tiếp tuyến của đường tròn tại b,c cắt nhay ở k .tia ko cắt (o) ở d,a (d nằm giữa k,o) gọi e là giao điểm của bd,ac A)góc kbd =góc kac B)4 điểm a,b,k,e thuộc cùng một đường tròn C)ke=kb

1. Tiger Woods, a famous golfer, ________ 50,000 dollars to star in an advert. A. is paid B. pays C. has paid D. was paying 2. The driver ________ in the accident. A. killed B. is killing C. has killed D. was killed 3. A lot of money ________ on that project so far. A. have been spent B. has been spent C. has spent D. have spent 4. As soon as the referee whistles, the game ________. A. kicked off B. was kicked off C. kicks off D. is kicked off 5. ________ to the party, they could hardly refuse to go. A. Having been invited B. Having invited C. To be invited D. Inviting 6. The greenhouse effect is a phenomenon that is caused when CO2 _______ and is trapped in the atmosphere. A. releases B. released C. is released D. has released 7. When I returned, I found that my car _______ away. A. had been pulling B. has been pulling C. has been pulled D. had been pulled 8. All planes _______ before departure. A. will check B. will be checked C. will have checked D. have checked 9. Tony had his car _______ by a mechanic. A. repair B. to repair C. repaired D. was repaired 10. The prince _______ into a frog by an evil sorceress. A. was turned B. was turning C. turned D. had turned 11. The fields _______ flooded now if it rained heavily. A. will have B. can be C. would have D. would be 12. If John _______ an alarm, the burglars would hesitate to break into his house. A. had installed B. had been installed C. installed D. was installed 13. Next month my salary ________ by ten percent. A. is going to raise B. will be raised C. will be risen D. is raising 14. Look. The cattle _______ grass in the field. A. is eating B. is eaten C. are being eaten D. are eating 15. My sister _______ in the kitchen at the moment. A. is cooking B. is being cooked C. cooks D. is cooked 16. _______ in 1636, Harvard is one of the most famous universities in the US. A. Founding B. Finding C. Founded D. Found 17. _______ in Cambodia, he grew up in Thailand. A. Bearing B. Born C. Borne D. Bear 18. A storm ________ across the north of England last night. A. swept B. was swept C. had swept D. was sweep 19. Many people _______ from the floods. A. rescued B. were rescued C. were rescuing D. rescue 20. Fire-fighters _______ hundreds of calls for help. A. receiving B. were received C. had been received D. received

Các bạn giúp mình nha . Mình cảm ơn rất nhiều

cho tam giác ABC, trên AB,AC lần lượt lấy điểm M và N. Biết AM=3cm, MB=2cm, AN=7,5cm, NC=5cm. a) chứng minh MN//BC b) Gọi I là trung điểm của BC, K là giao điểm của AI với MN. Chứng minh K là trung điểm của NM.