Gọi đường cao chung của 2 tam giác ABD và ACD là AH

Xét tam giác ABC có:

 AD là đường phân giác

=>\(\dfrac{DB}{DC}=\dfrac{AB}{AC}\)

=>\(\dfrac{DB}{DB+DC}=\dfrac{AB}{AB+AC}\)

=>\(\dfrac{DB}{BC}=\dfrac{6}{6+4}\)

=>\(\dfrac{DB}{5}=\dfrac{6}{10}\)

=>DB=3cm

CMTT:DC=2cm

Ta có:\(\dfrac{S_{ABD}}{S_{ACD}}=\dfrac{\dfrac{1}{2}.AH.BD}{\dfrac{1}{2}.AH.DC}=\dfrac{BD}{DC}=\dfrac{3}{2}\)

không để ý cái đề =)) tưởng có mỗi chia động từ

1.disturbed

2.went

3.slept

4.ate

5.was

6.laughed

7.flew

8.cost

9.had

10.were

đã thì htht r thì là j còn ago

a)\(4Al+3O_2->2Al_2O_3\)

b)\(S+O_2->SO_2\)

c)\(2KClO_3->2KCL+3O_2\)

d)\(2H_2O->2H_2+O_2\)

\(\left(\dfrac{7}{2}\times\dfrac{2}{7}\right)\times2=1\times2=2\)

1.     The land is polluted. The farmers are unable to grow crops.

If the land wasn't polluted. The farmers wouldn't unable to grow crops.

2.     The last time Jim visited London was two years ago.

Jim has not visited London for two years.

3.     Tornadoes can move objects easily.

Objects can be moved easily by tornadoes.

4.     It’s a pity I don’t have her number.

I wish I had her number

5.     “I am having a workshop on the Environment now”, Susan said.

Susan said that She was having a workshop on the Environment then

Khi dùng when có mấy trường hợp với mỗi trường hợp hãy nêu ra mẹo để nhận biết

short nhớ chuyển thành shortness mà ta cũng như lazy í còn câu 2 used to nghĩa là đã từng rồi thì cần gì vế when I was a student nữa

1.What is the distance between Vinh and Ha Noi city?

=>How far is it from Vinh to Ha Noi city?

2.I often walked to school when I was a student

=>I used to walk to school.

3.Although they are short , they still love playing sports

=>In spite of being shortness,they still love playing sports

4.The road was slippery,so they couldn't drive fast (Rewrite the sentence,using "Because"

Because The road was slippery,so they couldn't drive fast