cho tam giác ABC vuông cân tại A, đường cao AH. Từ điểm M bất kì trên cạnh BC (M không trùng với B và C )kẻ các đường thẳng song song với AC và AB ở D và cắt AC ở E c)C/m góc DHE=90độ

Cho tam giác ABC có A(1;2), B(-2;6), C(9;8) a. Chứng minh tam giác ABC vuông tại A b. Tính góc B tam giác ABC c. Xác định hình chiếu của A lên cạnh BC

Một tam giác ABC có cạnh đáy 3,5m.Nếu kéo dài cạnh đáy BC thêm 2,7m thì diện tích tam giác tăng thêm 5,265 m2 .thì diện tích hình tam giác ABC đó? Giúp mik với mik cần gấp mai mik thi rồi nha.

Giúp mình với' Giải các pt sau a,Căn (x^2+x)=x b, căn ( 1-x^2) - x^2 + 1 = 9 c, căn ( x^2 - 4x - 3) = x - 2

giúp mình với CÀNG NHANH CÀNG TỐT

Cac ban giup minh voi ONE OF THOSE DAYS It’s been one of those days and it isn’t over yet. First of all, I had to take the car to the garage to have the brakes ..repaired.. (0). The car was in a bad enough state, but we (36) ……………………... had it damaged even more by some idiot as we were waiting at the traffic lights the other day. He bumped into the back of the car and we told him he would have to pay to (37) ……………………... the car mended and he said he would (38) ……………………... it paid for by his insurance company. I certainly hope he does. The mechanic told me I could’ve (39) ……………………... myself killed driving the car and that we should’ve (40) ……………………... the brakes checked months ago. I left the car at the garage, then went straight to the hairdresser to have my hair (41) …………………….... I wanted to have (42) ……………………... cut really short, so it took ages. After that, I had to take Bill’s suit to the dry-cleaner’s to (43) ……………………... it cleaned after he had had wine (44) ……………………... over it at the party last night. Next, I had to go to the supermarket. When I had finished, my bags were so heavy I had to (45) ……………………... them delivered to my house - and that cost more money. And the day isn’t half over yet. I’ve still got to have my photograph (46) ……………………... for a new passport - my old one (47) ……………………... stolen when we had our house (48) ……………………... a few months back. What a life! Things can’t get worse, can they?

Every year people in many countries learn English. Some of them are young children. Others are teenagers. Many are adults. Some learn at school. Others study by themselves. A few learn English just by hearing the language in films, on telivision, in the office or among their friends. Most people must work hard to learn English. Why do all these people learn English? It's not difficult to anwer this question. Many boys and girls learn English at school because it is one of their subjects. Many adults learn English because it is useful for their work. Teenagers often learn English for their higher studies because some of their books are in English at the college or university. Other people learn English because they want to read newspapers or magezines in nglish. 1. Most people learn English by.................... A. themselves B. hearing the language on television C. working hard on the lesson D. speaking English to their friends 2. Teenagers learn English because................... A. It's useful for their higher studies B. It's one of their subjects. C. They want to master it. D. A and C are correct. 3. Why do other people learn English? A. They want to go abroad B. It's useful for their work. C. Most of their books are in English D. They want to read newspapers in English. Nếu đưa ra dẫn chứng ⇒ 5 sao + cảm ơn + CTLHN K hông có dân chứng ⇒ 3 sao + cảm ơn

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Cho tam giác ABC, đường cao AH, vẽ ngoài tam giác ấy các tam giác vuông cân ABD, ACE với góc B= góc C= 90độ a) qua điểm C vẽ đường thẳng vuông góc với BE cắt đường thẳng HA tại K b) ba đường thẳng AH, BE, CD đồng quy

Các cạnh của một tam giác có độ dài 4cm, 6cm và 6cm. Hãy tính góc nhỏ nhất của tam giác đó.