Cho tam giác ABC cân tại A có góc A = 40độ. Gọi H là giao điểm của đg phân giác AD và đg trung tuyến BE. Gọi K là giao điểm của đg vg góc vs AB tại B và đg vg góc vs AC tại C

a) So sánh AB và BC

b) C/m CH đi qua trung điểm của cạnh AB

c) C/m 3 điểm A, H, K thẳng hàng

Cho tam giác nhọn ABC có AD và BE là 2 dg cao cắt nhau tại H

a) Cho bt góc ABC > góc ACB. C/m rằng HC > HB

b) Vẽ HF vg góc vs AB tại F. C/m rằng 3 điểm C, H, F thẳng hàng

c) C/m rằng AB + AC > 2AD

d) C/m rằng HA + HB + HC < 2/3 (AB+AC+BC)

a) Xét tam giác ABH và tam giác ACH có:

AH chung( hv) HB=HC( H là trung điểm của cạnh BC-gt)

=> Tam giác ABH = tam giác ACH( ch-cgv)

b) Vì tam giác ABC cân tại A(gt)

=> + Góc B= Góc C(t/c)

+ AB=AC(đ/n) (1)

Xét tam giác BHM vg tại M( HM vg góc với AB-gt) và tam giác CHN vg tại N( HN vg góc vs AC-gt) có:

HB=HC(H là trung điểm của BC-gt)

Góc B= góc C( cmt)

=> Tam giác BHM= tam giác CHN( ch-gn)

=> MB= NC( 2 cạnh tương ứng) (2)

Vì H nằm giữa A và B(hv)

=> MA+MB=AB(t/c) (3)

Vì N nằm giữa A và C(hv)

=> NA+NC=AC(t/c) (4)

Từ (1) (2) (3) (4) => AM=AN

Sorry nha mk chỉ lm 2 câu đầu thui

câu 2 bài 20 sgk trang 27

IV. Choose the correct verb form in the brackets

1. When I (had / was having) a bath, someone (knocked / was knocking) the door

2. The rain (started / was starting) when I (went / was going) to the library

3. This time last Sunday I (walked / was walking) on this street

4. When I (saw / was seeing) Mr. Brown, he (drank / was drinking) coffee

5. Their parents (visited / were visiting ) the Statue of Libery while they (went / were going) shooping

6. I (met / was meeting ) an old friend while I (walked / was walking ) along the street

V. Choose the best answer

1. I hope the ...... can repair our car quickly

a. mechanic b.reporter c. nurse d. journalist

2. My ........always comes early so I get my letters before I go to work

a. chemist b. porter c. mailman d. engineer

3. My tooth doesn't stop hurting. I'll go and see my.................

a. actor b.dentist c. write c. teacher

4. She wants the ...............to make a special cake for her daughter's bỉthday

a. inspector b. musician c. architect c. butcher

5. THat.................sells very good meat

6. Ask the shop............where the washing powder is

a. nurse b. assistant c. baker d. mailman

7. The................is showing them his plans of the new building

a. doctor b. pianist c. architest d. dance

8. The boss wants his.......................... to type some letters

a. secretary b. novelist c. journalist d. musician

9.The ...............gives the patient his madicine twice a day

a. butcher b. nurse c. operator d. porter

10. The.............will take your suitcases to your room

a. porter b. author c. engineer d. hairdresser

VI. Find a mistake in each sentences and correct it

1. Mr. Brown aets a few fruit for breakfast

2. I have less books in English than my classmates

3. We are going to have a two-weeks summer vacation in Hue next month

I. Combine these pairs of questions into using Alternative Question:

1. Can you speak English? Can you speak French?

.................................................................................................................................?

2. Is she watching TV? Is she studying?

.................................................................................................................................?

3. Did they go to the movies? Did they stay at home?

................................................................................................................................?

4. Would you like some rice? Would you like some soup?

................................................................................................................................?

5. Are you a dentist? Are you a doctor?

...............................................................................................................................?

6. Is the house expensive? Is the house cheap?

..............................................................................................................................?

7. Will you go to school? Will you stay at home tomorrow?

............................................................................................................................?

8. Do you think English is difficult? Do you think English is easy?

...........................................................................................................................?

9. Does Rosie love playing badminton? Dóe she love swimming?

..........................................................................................................................?

10. Is you new teacher sociable? Is he strict?

..........................................................................................................................?

II. Change these Tag Questions into Yes/No Questions or Yes/No into Tag Questions:

1. You like chocolate, don't you?

..........................................................................................................................?

2. Is he good at English?

..........................................................................................................................?

3. Nam was at home this morning, wasn't he?

..........................................................................................................................?

4. She is doing her homework, isn 't she?

..........................................................................................................................?

5. You will send her a letter, won't you?

..........................................................................................................................?

6. Mrs. Thu stayed at home last Sunday, didn't she?

..........................................................................................................................?

7. The children have never been to Nha Trang, haven't they?

..........................................................................................................................?

8. She should do morning exercises, shouldn't she?

..........................................................................................................................?

9. Have the girls learned since 2p.m?

..........................................................................................................................?

10. Can your sister play the guitar?

..........................................................................................................................?

11. Do they speak French?

..........................................................................................................................?

12. Was Mr.Allem typing at that time?

.........................................................................................................................?

13. Are your parents going to ho chi minh city thus Sunday?

.........................................................................................................................?

14. Did the woman phone the police?

........................................................................................................................?

Bài 1: Tìm các cụm danh từ, cụm động từ, cụm tính từ trong đoạn trích sau và ghi chú thích các bộ phận của từng cụm bằng cách gạch chân:

"... Ngày xưa, có hai vợ chồng ông lão đánh cá ở với nhau trong một túp lều nát trên bờ biển. Ngày ngày chồng đi thả lưới, vợ ở nhà kéo sợi. Một hôm, người chồng ra biển đánh cá. Lần đầu kéo lưới thì thấy có bùn, lần thứ nhì kéo chỉ thấy cây rong biển, lần thứ ba kéo lưới thì bắt dc một con cá vàng..."

Luyện tập Bài 38(SGK, trang 22)

Bài 22(SGK tr89)

Bài 22(SGK tr 89)