Bài 7: cho tam giác ABC cân tại A. Gọi D, E, F lần lượt là trung điểm của BC, CA, AB. Trên tia đối của tia FC lấy điểm H sao cho F là trung điểm của CH. Các đường thẳng DE và AH cắt nhau tại I. Chứng minh:

a. BDIA là hình bình hành.

b. BDIH là hình thang cân.

c. F là trọng tâm của tam giác HDE.

vì sao nói công xã Pari là cuộc cách mạng vô sản không triệt để?

Sử dụng các từ gợi ý và viết lại thành câu hoàn chỉnh:

1. Those buses/ not going/ airport/ neither/ taxis.

2. You/ not/ want/ sell/ house last year?

3. He/ stop/ smoke/ save money.

4. My brother/ not drive/ carefully/ I.

5. It/ difficult/ prevent/ people/ park here.

Viết lại câu sao cho nghĩa không đổi:

 1. There's no more rice.

-> We've................................................................

2. I wasn't early enough to say goodbye to her.

-> I didn't................................................................

3. He managed to open the dooe.

-> He finally ...........................................................

4. Smoking is harmful to your health.

-> It is worthless .....................................................

5. Somebody broke the window just after they left for the shop.

-> Hardly ...................................................................

6. It took her two hours to explain the lesson.

-> She explained .......................................................

7. She'd rather not have fish for lunch.

-> She doesn't ...........................................

8. No one could know her reaction to the problem.

-> Her reaction ...............................................

9. He always abides by his word.

-> He never ........................................................

10. I have lived here since 1999 and I can stand the noise.

-> I am .................................................................

11. They refused to accept her application for the job.

-> Her ..................................................................

12. You will have to study harder for the exam.

-> You don't .........................................................

13. It was so cold that I wore a warm coat.

-> I felt ..............................................................

14. It was kind of you to help the poor.

-> You were ......................................................

15. He wasn't told about the accident.

-> They .............................................................

15. He wasn't told about the accident.

-> They .............................................................

Viết lại câu sao cho nghĩa không đổi:

-> We've................................................................

2. I wasn't early enough to say goodbye to her.

-> I didn't................................................................

3. He managed to open the dooe.

-> He finally ...........................................................

4. Smoking is harmful to your health.

-> It is worthless .....................................................

5. Somebody broke the window just after they left for the shop.

-> Hardly ...................................................................

6. It took her two hours to explain the lesson.

-> She explained .......................................................

7. She'd rather not have fish for lunch.

-> She doesn't ...........................................

8. No one could know her reaction to the problem.

-> Her reaction ...............................................

9. He always abides by his word.

-> He never ........................................................

10. I have lived here since 1999 and I can stand the noise.

-> I am .................................................................

11. They refused to accept her application for the job.

-> Her ..................................................................

12. You will have to study harder for the exam.

-> You don't .........................................................

13. It was so cold that I wore a warm coat.

-> I felt ..............................................................

14. It was kind of you to help the poor.

-> You were ......................................................

15. He wasn't told about the accident.

-> They .............................................................

15. He wasn't told about the accident.

-> They .............................................................

Viết lại câu sao cho nghĩa không đổi:

1. There's no more rice.

-> We've................................................................

2. I wasn't early enough to say goodbye to her.

-> I didn't................................................................

3. He managed to open the dooe.

-> He finally ...........................................................

4. Smoking is harmful to your health.

-> It is worthless .....................................................

5. Somebody broke the window just after they left for the shop.

-> Hardly ...................................................................

6. It took her two hours to explain the lesson.

-> She explained .......................................................

7. She'd rather not have fish for lunch.

-> She doesn't ...........................................

8. No one could know her reaction to the problem.

-> Her reaction ...............................................

9. He always abides by his word.

-> He never ........................................................

10. I have lived here since 1999 and I can stand the noise.

-> I am .................................................................

11. They refused to accept her application for the job.

-> Her ..................................................................

12. You will have to study harder for the exam.

-> You don't .........................................................

13. It was so cold that I wore a warm coat.

-> I felt ..............................................................

14. It was kind of you to help the pỏo.

-> You were ......................................................

15. He wasn't told about the accident.

-> They .............................................................

Cho tam giác ABC có trung tuyến AM, I là một điểm thuộc đoạn thẳng AM , BI cắt AC ở D.

a. Nếu AD =1/2 DC. CM : IM = IA.

b. Nếu IM = IA. CM: AD = 1/2 DC ; ID = 1/4 BD.

c. Nếu AD = 1/2 DC. Trên canh AB lấy điểm e sao cho AB = 3AE. CM : BD,CE,AM đồng quy.

Bài 13: Cho tam giác ABC có AB<AC, AH là đường cao. Gọi M,N,K lần lượt là trung điểm của AB,AC,BC. 

a. Chứng minh: MNKH là hình thang cân.

b. Trên tia AH và AK lần lượt lấy điểm E và D sao cho H là trung điểm của AE và K là trung điểm của AD. Chứng minh tứ giác BCDE là hình thang cân.