Cho ∆ABC có AB= AC = 5cm, BC = 6CM. Kẻ AK vuông góc với BC ( K ∈ BC). a) Chứng minh rằng KB = KC và 𝐵𝐴𝐾 ̂ =𝐶𝐴𝐾 ̂ b) Tính độ dài AK c) Kẻ KE vuông góc với AB ( E ∈ AB) , KD vuông góc với AC ( D ∈ AC). Chứng minh rằng ∆KDE là tam giác cân. d) Chứng minh rằng DE//BC e) Trên tia đối của tia AB lấy điểm M sao cho AB = AM. Chứng minh răng MC vuông góc với BC

tìm tổng của tất cả các số nguyên thỏa mãn; |x|<hoặc=4 gấp.giúp mk nha

1 Mark the letter A, B, C or D to indicate the most suitable response to complete each of the following exchanges. “My favorite leisure activity is people watching.” “_______” A: That’s all right. B: OK. That’s very kind of you C: That sounds so weird! D: Sure. It’s very entertaining. Choose the best answer a, b, c or d to complete the sentence. Question 5. How much time do you spend _______ leisure activities? A: on B: for C: with D: in 4 Choose the sentence so that it has similar meaning to the first one. Question 22. She likes to hang out with friends on Saturday evening. A: She’s fancy hanging out with friends on Saturday evening. B: She’s keen in hanging out with friends on Saturday evening. C: She’s interested in hang out with friends on Saturday evening. D: She’s interested in hanging out with friends on Saturday evening. 5 Read the passage carefully, then choose the correct answers. The latest addiction to trap thousands of people is the Internet, which has been blamed for broken relationships, job losses, financial ruin, and even suicide. Psychologists now recognize Internet Addiction Syndrome (IAS) as a new illness that could cause serious problems and ruin many lives. IAS is similar to other problems like gambling, smoking and drinking: addicts have dreams about the Internet; they need to use it as the first thing in the morning; they lie to their parents and partners about how much time they spent online; they wish they could cut down, but are unable to do so. A recent study found that many users spend up to 40 hours a week on the Internet. Some of the addicts are teenagers who are already hooked on computer games and who find it very difficult to resist the games on the Internet. Internet addicts find it hard ___________. A: to use the Internet in the morning B: to spend more time on the Internet C: to lie about the time they spent online D: to spend less time on the Internet 6 Read the passage carefully, then choose the correct answers. The latest addiction to trap thousands of people is the Internet, which has been blamed for broken relationships, job losses, financial ruin, and even suicide. Psychologists now recognize Internet Addiction Syndrome (IAS) as a new illness that could cause serious problems and ruin many lives. IAS is similar to other problems like gambling, smoking and drinking: addicts have dreams about the Internet; they need to use it as the first thing in the morning; they lie to their parents and partners about how much time they spent online; they wish they could cut down, but are unable to do so. A recent study found that many users spend up to 40 hours a week on the Internet. Some of the addicts are teenagers who are already hooked on computer games and who find it very difficult to resist the games on the Internet. The word ‘it’ in paragraph 2 refers to ___________. A: dream B: computer C: the Internet D: IAS 7 Choose the sentence so that it has similar meaning to the first one. Question 25. DIY skills aren’t as hard to learn as I think. A: DIY skills are easier to learn than I think. B: DIY skills are easier to learn. C: DIY skills are easier to learn as I think. D: I think DIY skills are easier to learn. 8 Choose the best answer a, b, c or d to complete the sentence. Question 7. On YouTube you can find many videos on _______ all aspects of your English. A: improving B: working C: surfing D: taking

Giúp mình với Tìm x,y x²-x+y²+y+1/2=0

cho Tam giác ABC cân tại A ( A<90 độ )vẽ BD vuông góc AC CE vuông góc AB Gọi H là giao điểm của BD CE a) cm tam giác ABD = tam giác ACE b)cm tam giác AED cân c) cm AH là đừng trung trực của ED d) trên tia đối tia DB lấy điểm K sao cho DK=DB cm góc ECB= góc DKC

• Đọc đoạn văn sau và chọn câu trả lời đúng nhất. Experts think that it is a good idea for children to learn not just one, but two foreign languages. They say that learning two foreign languages develops children’s minds and increase their knowledge of other cultures. The experts also believe that the two languages children learn should be completely different from one another, for example English and Chinese, or French and Japanese. In addition, they say that children should start to learn foreign languages as early as possible, from the age of about six. • According to experts, children ________________. A. shouldn’t learn more than two foreign languages. B. should learn just one foreign language C. should learn two foreign languages D. shouldn’t learn foreign languages • What does the word “They” in line 2 refer to? A. experts B. children C. languages D. cultures • Children should learn ________________ A. two foreign languages which are the same. B. one language C. two foreign languages which are completely different from one another D. all are correct • Which of the following is not true? A. Children should start to learn foreign languages early. B. Children should start to learn foreign languages from the age of about six. C. Children should start to learn foreign languages late. D. Learn foreign languages is good for children.

để điều chế đc 48 gam khí oxi thì cần bao nhiêu mol kali corat (KCLO3) để phân hủy

Cho ∆ABC đều, kẻ AH vuông góc với BC tại H. Trên tia đối của tia BC lấy điểm E sao cho BE = BC. Trên tia đối của tia CB lấy điểm D sao cho CB = CD. a) Chứng minh rằng ∆AEB = ∆ADC b) Từ D kẻ DF vuông góc với AC tại F. Chứng minh rằng ∆CHF cân c) Chứng minh rằng AD//HF d) Từ B kẻ BM vuông góc AE tại M, từ C kẻ CN vuông góc với AD tại N. Gọi I là giao điểm của BM và CN. Chứng minh AI là phân giác của 𝐵𝐴C

Dẫn hỗn hợp gồm 0,01 mol CH4;0,02 mol C2H4 và 0,03 mol C2H2 lần lượt đi qua bình (1) chứa lượng dư dung dịch AgNo3 trong NH3;bình (2) chứa dung dịch Br2 (dư),thấy khối lượng dung dịch trong bình (1) giảm a gam và khối lượng Br2 trong bình (2) đã phảnưng là b gam.Tổng giá trị a+b là bao nhiêu?

VI. Find and correct a mistake in each sentence 46. Use roads careful so we may be able to use them for a long time. A B C D 47. I saw some cars stop by the police. A B C D 48. The car was too expensive for him buying. A B C D 49. My father is a careful driver and he doesn’t drive too fast or dangerous. A B C D 50. On the way we passed, there were many interested sights. A B C D 51. The old house in the end of the road has been sold. A B C D 52. Despite of taking a taxi, he arrived late. A B C D 53. The gate are closed so that the children can’t run into the road. A B C D 54. The train had just left when I arrive at the station. A B C D 55. It is important to learn use the roads properly and safely. A B C D 56. I see a serious accident while I was standing at the bus stop. A B C D