1. Progress in science is being made day after day. → People are making progress in science day after day.

2. A French architect designed the palace.

3. They have paved the road in front of my house.

4. You can see that they haven't washed the dishes.

5. They will not increase our salaries this year.

6. Didn't they build that theatre two years ago?

7. They may discuss the problem again.

8. They have offered my brother a well – paid job.

9. People reported that the war started again in South American.

10. He told me that his football team had played well last season.

2. A French architect designed the palace.

3. They have paved the road in front of my house.

4. You can see that they haven't washed the dishes.

5. They will not increase our salaries this year.

6. Didn't they build that theatre two years ago?

7. They may discuss the problem again.

8. They have offered my brother a well – paid job.

9. People reported that the war started again in South American.

10. He told me that his football team had played well last season.

2. The man is believed to have been killed by terrorists.

3. The company is thought to be planning a new advertising campaign.

4. The President was reported to have suffered a heart attack.

5. The man is alleged to have been driving at 110 miles an hour.

6. The expedition is known to have reached the South Pole in May.

7. There is said to be a secret tunnel between them.

8. She is considered to have been the best singer that Australia has ever produced.

9. The weather is expected to be good tomorrow.

10. The Prime Minister and his wife are believed to have separated.

Kết luận nào sau đây đúng ?

A. Hai góc kề nhau có tổng số đo bằng 90 độ

B. Hai góc phụ nhau có tổng số đo bằng 180 độ

C. Hai góc bù nhau có tổng số đo bằng 90 độ

D. Hai góc bù nhau có tổng số đo bằng 180 độ

Kết luận nào sau đây đúng ?

A. Hai góc kề nhau có tổng số đo bằng 90 độ

B. Hai góc phụ nhau có tổng số đo bằng 180 độ

C. Hai góc bù nhau có tổng số đo bằng 90 độ

D. Hai góc bù nhau có tổng số đo bằng 180 độ

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mình nghĩ nên đẩy ý b) lên trước vì đã tính AC đâu mà có tỉ số :D

a) Áp dụng định lí Pythagoras cho ΔvuôngABC ta có :

BC² = AB² + AC²

=> \(AC=\sqrt{BC^2-AB^2}=\sqrt{15^2-9^2}=12\left(cm\right)\)

b) Tỉ số hai đoạn thẳng AB và AC : AB/AC = 9/12 = 3/4

c) Vì CD là phân giác của ^C nên theo tính chất đường phân giác trong tam giác ta có : \(\frac{AD}{AC}=\frac{BD}{BC}\)

Áp dụng tính chất dãy tí số bằng nhau ta có : \(\frac{AD}{AC}=\frac{BD}{BC}=\frac{AD+BD}{AC+BC}=\frac{AB}{AC+BC}=\frac{9}{12+15}=\frac{1}{3}\)

=> \(\hept{\begin{cases}\frac{AD}{AC}=\frac{1}{3}\\\frac{BD}{BC}=\frac{1}{3}\end{cases}}\Rightarrow\hept{\begin{cases}AD=\frac{1}{3}AC=4\left(cm\right)\\BC=\frac{1}{3}BC=5\left(cm\right)\end{cases}}\)

This is the schedule for my one-day visit to Moscow. On the first day we arrive at Moscow Vnukovo Airport at 7.30 A.M and take a ride to a hotel nearby. Then, we go to Kremli - the historical and geographical center of Moscow. It has been recognized by UNESCO as a world cultural heritage. Next, we go to Red Square. It is near Kremli and is the most popular square in Moscow. Then, we go to GUM department store to buy many things. At about 12 A.M, we go to Tiberio Restaurant. After lunch, we return the hotel and go to sleep. At about 2 P.M, we wake up and go to Moscow River to go for a walk along the river or enjoying a boat tour. Enjoying on the river, you also see the beautiful scenery. At about 7 P.M, we have dinner in Old City Restaurant. After dinner, we return the hotel and arrange our luggage for to go home.

Answer:

- '' It is near Kremli and is the most popular square in Moscow. '' => It is near Kremli and it's / it is the most popular square in Moscow

- '' After lunch, we return the hotel and go to sleep. '' => After luch, we return / turn back to the hotel and go to sleep.

- '' At about 2 P.M, we wake up and go to Moscow River to go for a walk along the river or enjoying a boat tour. '' => At about 2 P.M, we wake up and go to Moscow River to go for a walk or enjoy...

- '' Enjoying on the river, you also see the beautiful scenery. '' => Theo mình thì bạn nên thay đổi sang trạng ngữ khác cho câu đỡ bị cứng. Mình nghĩ cũng nên đổi '' scenery '' thành '' sights '' hoặc '' scenes '', chuyển câu thành '' you also see many beautiful scenes / sights ''

- '' After dinner, we return the hotel and arrange our luggage for to go home. '' => Theo mình bạn nên bỏ '' for '' đi

 Ta có: BH vuông góc AM và CK vuông AM

=> BH // CK

Ta chứng minh được ΔBHM = ΔCKM (g-c-g)

=> BH = CK

a) Xét\(\Delta OAM\)và \(\Delta OAN\)có:

\(\hept{\begin{cases}OA:chung\\gócAOM=gócAON\\gócOAM=gócOAN\left(=90^0\right)\end{cases}}\)

\(\Rightarrow\Delta OAM=\Delta OAN\left(ch-gn\right)\)

\(\Rightarrow OM=ON\left(đpcm\right)\)

b) Xét \(\Delta OEM\)và \(\Delta OEN\)có:

\(\hept{\begin{cases}OE:chung\\gócMOE=gócNOE\\OM=ON\end{cases}}\)

\(\Rightarrow\Delta OEM=\Delta OEN\left(c.g.c\right)\)

\(\Rightarrow gócOEM=gócOEN\left(đpcm\right)\)