Từ một tấm bìa có hình tam giác vuông OAB có cạnh huyền AB = 13cm; một cạnh góc vuông OB = 5cm. Chọn cạnh góc vuông còn lại OA làm trục quay chung quanh tấm bìa đã chọn tạo thành hình nón. Biết diện tích đường tròn đáy là S = \(\pi\).OB²; và công thức tính thể tích của hình nón tạo thành là V = \(\frac{1}{3}\).S.h với h = OA. Tính thể tích của hình nón tạo thành.

Khu đất hình chữ nhật có chu vi bằng 38m. Biết chiều dài hơn 2 lần chiều rộng là 7m. Tính diện tích của khu đất lúc đầu?

Bạn Long đặt mắt vào ống nhòm trên đài quan sát của toà nhà Landmark cao khoảng 450m so với mặt đất thì thấy một điểm B trên mặt đất với khoảng cách tối đa là bao nhiêu km? Biết rằng bán kính Trái Đất gần bằng 6400 km.

Cho phương trình x² - (3m + 1)x + 2m² + m - 1 = 0 (x là ẩn số).

a) Chứng minh rằng phương trình luôn luôn có 2 nghiệm phân biệt với mọi giá trị của m.

b) Gọi x₁, x₂ là các nghiệm của phương trình. Tìm m để biểu thức A = x₁² + x₂² - 3x₁x₂ đạt giá trị lớn nhất.

Exercise 4: Choose the correct answer.

1) What's the name of a man ... gave us a lift?

A. he

B. what

C. which

D. who

2) Were you able to locate the person ... wallet you found?

A. which

B. that his

C. whose

D. that's

3) My friend Nigel, ... works in the city, earns much more than I do.

A. that

B. which

C. who

D. whose

4) Everyone ... the building was searched by the police.

A. enter

B. entered

C. entering

D. enters

5) The severe drought ... occured last summer ruined the corn crop.

A. that it

B. which it

C. it

D. that

6) Florida, ... the Sunshine State, attracts many tourists every year.

A. is

B. known as

C. is known as

D. that is known as

7) Neil Armstrong, the first person ... on the moon, reported that the surface was fine and powdery.

A. that set foot

B. set foot

C. setting foot

D. to set foot

8) Atlanta is the city ... the Olympic Games were held in 1996.

A. that

B. when

C. where

D. which

9) Ann quit her job at the advertising agency, ... surprised everyone.

A. which

B. that

C. who

D. that it

10) Is this the address to ... you want the package sent?

A. where

B. that

C. which

D. whom

11) They left me at the bus stop ... they had met me the week before.

A. where

B. which

C. when

D. that

12) Little Women, ... in 1868, is my favorite book.

A. is a novel published

B. a novel published

C. a novel was published

D. was a novel published

13) I have three brothers, ... are businessmen.

A. all of which

B. all of those

C. all of whom

D. all of who

14) The chemistry book ... was a little expensive.

A. that I bought it

B. I bought that

C. what I bought

D. I bought

15) We passed shops ... windows were decorated for Christmas.

A. the

B. their

C. which

D. whose

16) "Why do you get up at 4:00 am?" - Because it's the only time ... without being interrupted.

A. when I can work on my book

B. when I can work on my book at

C. when I can work on my book then

D. at when I can work on my book

17) I didn't believe them at first but in fact everything ... was true.

A. they said

B. that they said

C. what they said

D. to which they said

18) New York, ... last year, is a nice old city.

A. I visited

B. that I visited

C. which I visited

D. whom I visited

19) Do you remember Mrs. Goddard, ... taught us English composition?

A. who

B. whom

C. that

D. which

20) Only a few of movies ... on TV are suitable for children.

A. which show

B. showing

C. shown

D. are shown

Exercise 3: Rewrite the following sentences in good English.

1) Rupert knows the family who's house is for rent.

2) I've met many people, some of them are from my country.

3) The reason because I didn't know was that no one had told me.

4) There were a lot of people waited in a long line outside the box office.

5) Einstein who failed his university entrance exam discovered relativity.

6) I can't find my diary, what is a real nuisance.

7) Lake Superior, that lies on the US Canadian border, is the largest lake in North America.

8) My favorite place in the world is a small city is located on the southern coast on Brazil.

9) The nice couple with who we went on holiday has just moved in next door.

10) I ran into a woman with that I had gone to elementary school.