\(\dfrac{13}{2}\) : 4\(\dfrac{2}{3}\): 2

= \(\dfrac{13}{2}\): \(\dfrac{14}{3}\):2

= \(\dfrac{13}{2}\) \(\times\) \(\dfrac{3}{14}\):2

=  \(\dfrac{39}{28}\) : 2

= \(\dfrac{39}{28}\) \(\times\) \(\dfrac{1}{2}\)

= \(\dfrac{39}{56}\)

tam giác ABC vuông tại A có
AB=sin30⁰.BC
BC=80:1/2
BC=160m
=>AC²=BC²-AB²
    AC²=160²-80²=19200
    AC=80\(\sqrt{3}\) m
tam giác ABD vuông tại A có
AB=sin45⁰.AD
AD=80:\(\dfrac{\sqrt{2}}{2}\)
AD=\(80\sqrt{2}\) m
CD = AC-AD=\(80\sqrt{3}-80\sqrt{2}\approx25m\)

1. My brother (listen)listened  to music last night. 

2. When I came to see Peter, he (do)was doinghis homework.

3. Mr Manh wishes he (be)were in Paris now.

4. Up to present, Mr John (write)has written more than one hundred novels.

5. Tim (always blame)is always blaming his faults on the others.

6. Mary (write)writes her pen pal once a week.

7. When the milkman came, my family (have)was having dinner.

8. Lan and Maryam (not respond)haven't responded each other for along time.

9. If she (study)studies harder, she (pass)will pass the examination.

10. It's important that you arm (operate)be operated now

1. My brother (listen)listened  to music last night. 

2. When I came to see Peter, he (do)was doinghis homework.

3. Mr Manh wishes he (be)were in Paris now.

4. Up to present, Mr John (write)has written more than one hundred novels.

5. Tim (always blame)is always blaming his faults on the others.

6. Mary (write)writes her pen pal once a week.

7. When the milkman came, my family (have)was having dinner.

8. Lan and Maryam (not respond)haven't responded each other for along time.

9. If she (study)studies harder, she (pass)will pass the examination.

10. It's important that you arm (operate)be operated now

One of the biggest environmental impacts of human activities is air pollution

268cm²

268cm² nhé

268cm²

\(NH_3\) chạy qua \(\left(NH_4\right)_2CO_3\) rồi sao tạo  \(NH_4NO_3\) được: )

Cân bằng PTHH:

\(18HCOONa+4AgNO_3+14NH_3+6H_2O\rightarrow4Ag+9Na_2CO_3+9\left(NH_4\right)_2CO_3\)

Câu 14: B

Câu 15: A