Cho DDEF vuông tại D có = 300, Kẻ DH ^ EF; HN ^ ED; HM ^ DF.
a/ Chứng minh: DMHN là hình chữ nhật và MN =
b/ Cứng minh: DN.DE = DM.DF
c/ Chứng minh: \(\frac{DM^2}{EH^2}+\frac{DM^2}{DH^2}\text{=}1\)
d/ Đường trung tuyến DK của DDEF cắt MH tại I. Chứng minh: \(\frac{1}{DH^2}+\frac{1}{DI^2}\text{=}\frac{1}{HN^2}\)
Câu 1: Cho DABC vuông tại A, BC = 28 cm, đường cao AH. Tính AH và AB biết tỉ số của BH và CH là 2 và 5.
Câu 2: a/ Sắp xếp các tỉ số lượng giác sau theo chiều tăng dần: sin370, cos140, cos750, sin800.
b/ Tính giá trị của biểu thức: 5.tan400.tan500 - cos2470 - cos2430 - 3
Câu 3: Giải DABC vuông tại C có AB = 20cm; = 350.
Câu 4: Cho DDEF vuông tại D có = 300, Kẻ DH ^ EF; HN ^ ED; HM ^ DF.
a/ Chứng minh: DMHN là hình chữ nhật và MN =
b/ Cứng minh: DN.DE = DM.DF
c/ Chứng minh:
d/ Đường trung tuyến DK của DDEF cắt MH tại I. Chứng minh:
Exercise 1: Choose the best answer: 1 . "Those eggs of different colors _____ in Russia ". a. were painted b. were paint c. were painting d. painted 2. All flights _____ because of fog. a. is cancelled b. was cancelled c. were cancelled d. served 3 . The dinner _____ in the dinning room. a. is serving b. serves c. is being served d. served 4. I _____ listening and speaking. a. is being taught b. am being taught c. are being taught d. has taught 5. Gold_____ in California in the nineteenth century. a. was discovered b. has been discovered c. was discover d. they discovered 6. "Where's the old chicken coop?" "It_____ by a windstorm last year." a. destroy b. is destroyed c. was destroyed d. destroyed 7. "We're still looking for Thomas". " He hasn’t _____ yet?". a. been found b. to find c. found d. being found 8. All planes_____ before departure. a. will checked b. will has checked c. will be checked d. will been checked 9 . Diana _____ since she was four. a. has been dancing b. has been danced c. is dancing d. was danced 10. This room _____ by me every day a. was cleaned b. has cleaned c. cleaned d. is cleaned Exercise 2: Chuyển các câu sau sang thể bị động. 1. The waiter brings me this dish. 2. Our friends send these postcards to us. 3. Their grandmother told them this story when they visited her last week. 4. Tim ordered this train ticket for his mother. 5. She showed her ticket to the airline agent. 6. Jim baked this cake yesterday. 7. They are going to buy a new apartment next year. 8. The shop assistant handed these boxes to the customer. 9. The board awarded the first prize to the reporter. 10. Nam has just sent the Christmas cards to his family. 11. The committee appointed Alice secretary for the meeting. 12. Tom will give Anna a ride to school tomorrow. 13. They keep this room tidy all the time. 14. We gave Ann some bananas and some flowers. 15. They are moving the fridge into the living room now
1.Do you prefer staying at home to going out in the evening? Why?
2.Do you think modern lifestyles give people enough time for leisure?
3.What do you think are the good points and the possible bad points about having leisure time?
4.Do you like to travel in your holidays?