Bài 1 : Cho hình chữ nhật ABCD có AB = 8cm , BC = 6cm . Qua D kẻ đường thẳng m vuông góc DB , đường thẳng m cắt tia BC tại E . Kẻ CH vuông góc DE tại H 

a, Chứng minh △BDE đồng dạng △DCE

b, Chứng minh DC² = CH . DB 

c, Gọi giao điểm hai đường chéo của hình chữ nhật ABCD là O . Hai đường OE và HC cắt nhau tại I . Chứng minh I là trung điểm HC và S△BCH / S△EBD . 

d, Chứng minh 3 đường thẳng OE , DC , BH đồng quy . 

CÁC BẠN GIÚP MÌNH VỚI Ạ =((((((((((((((((((((

1. I don’t know her number, so I don’t ring her up

 If I ………

2. I don’t know the answer, so I can’t tell you.

 If I …………………

3. When you ask me for the book, I will lend it to you.

Unless you ……………………….

4. I feel miserable because Kate doesn’t love me.

 If Kate ……………………….

5. I won’t go to the party because I’m not feeling well.

 I would ………………….

6. There are too many cars. As a result, our planet is polluted.

 If there ………………………………

7. You are so nervous because you drink too much coffee.

 If you ……………………………….

8. As I haven’t got money, I can’t buy a new car.

 If ………………………………………….

9. I am in this class because I cannot speak perfect English.

 If I …………………………………….

10. I am very bad at English; I can't help you with your English exercises.

 If I ……………………….

11. He isn’t a good runner because he doesn’t train every day.

  If he ………….

12. Peter is fat because he eats so many chips.

 If Peter ………………….

13. His parents are away on holiday. He really needs their help now.

 He wishes ………….

14. Mike doesn't feel well today. He can't go out with his friends.

 Mike wishes ………

15. Peter is working on two jobs. He can’t help you fix your computer right now.

 If Peter …………………………….

GIÚP MÌNH VỚI  Ạ .. MÌNH CẢM ƠN =)))))))))))))))))

Ex 1 : Viết lại câu dưới dạng câu điều kiện 

1. You won’t lose weight if you eat so much,

  If you …………………….

2. Hurry up or you will be late for the last train.

  If you …………

3. I will feel relaxed this weekend if I finish all my work by next Friday.

  I won’t …………………

4. If you don’t deal with your stress, your health will suffer.

Unless you ………………………………………….

5. Stress hormones will stay in your body if you don’t do some exercise.

Unless you ……………….

6. You will feel very stressed if you don’t try to relax.

 You will ……………………………….

7. Keep silent or you’ll wake the baby up.

 If you ………………………….

8. Don’t go out in the rain because you’ll get wet.

If you ………………………

9. I won’t enjoy the film if you aren’t with me.

 Unless ………

10. Stop talking or you won’t understand the lesson.

If you ……………………………

11. You should take a map because you might get lost in those mountains.

 In case you …………………….

12. If Joe doesn't change his ways, he will end up in prison.

 Unless Joe ………………………….

13. If he doesn't work harder, he'll lose his job.

 Unless ………………………………….

14. Joan will stay on at school unless she finds a good job before September.     

 If Joan ………………….

15. Unless someone has a key, we can't get into the house.

 We can ………….

16. I’ll call the teacher if you don’t leave me alone.

 Unless you ………………………….

17. When you ask me for the car, I will lend it to you.

 Unless …………….

18. Don’t go out in the rain because you will get wet.

 If you …………………….

19. Walk faster or you will miss the bus.

 If you ………………………………….     

20. I won’t enjoy the film if you aren’t with me.

 Unless ……………………….

21. You must leave home early or you will miss the flight

 If you …………………………………….

22. John will pass the driving exam if he isn’t nervous

 Unless John …………….

23. They will go on holiday if they have time.

 Unless they …………….

24. You have to get up early or you will be late for school.

 If you …………….

25. I'll only help you if you promise to try harder.

 Unless …………………….

26. He will take a taxi if it rains.

 Unless …………….

27. Unless he phones immediately he won't get any information.

 If he ………………………….

GIÚP MÌNH VỚI :33333333

Bài 1 Tính giá trị biểu thức 

a. \(\sqrt{0,16}\)+ \(\sqrt{0,04}\) - \(\sqrt{0,25}\)

b.\(\sqrt{85^2-84^2}\) - \(\sqrt{26^2-24^2}\)