Độ dài cạnh đối diện với góc 30 độ là 9cm

a) Xét tứ giác ADHE có 

\(\widehat{ADH}\) và \(\widehat{AEH}\) là hai góc đối

\(\widehat{ADH}+\widehat{AEH}=180^0\left(90^0+90^0=180^0\right)\)

Do đó: ADHE là tứ giác nội tiếp(Dấu hiệu nhận biết tứ giác nội tiếp)

8. As it is raining heavily, we can't go on a picnic

9. I suggest (that) you should get a plumber to check the pipes

10. If you don't succeed, you'll have to try it again

11. If she had enough money, she would buy the dictionary

12. I suggest using gas instead of burning coal

13. I suggest you should install a burglar alarm in your house

14. If we recycle, we will save natural resources

15. If you don't hurry up, you will be late for work

16. If you work too much, you will be tired

17. I suggest putting different kinds of.....

18. Lan broke the glass as she was careless

19. If you litter the place around you, it will be a junk yard

20. Paul suggested using public transportation

21. If she doesn't reduce the use of water and electricity, she will have to.....

22. Since the weather was snowy, we postponed our soccer match

23. Tan suggested that Lam should buy a car

24. Lan suggested that I should look for another job

25. The scientist suggested using public transportation instead of private vehicles

26. giống c12

27. The principle is pleased that the students in grade 9 are good helpers

28. If we put garbage into the bins, we will minimize pollution

29. If you are careless, you will broke the vase

30. If you don't stop cutting trees, I will call the police

31. If you use electricity to catch fish, you will be fined heavily

32. I'm sure that that boy will have a test.....

33. We are disappointed that you threw the rubbish on the street

34. It is extremely important that all of us work together to protect the environment

35. I'm sorry that I couldn't do anything to help you

36. He is sure that environmental pollution in this area can be controlled

37. She was annoyed that he damaged the car yesterday

\(5,\\ a,=x^4+4x^2+4-4x^2=\left(x^2+2\right)^2-4x^2=\left(x^2-2x+2\right)\left(x^2+2x+2\right)\\ b,=x^4+16x^2+64-16x^2=\left(x^2+8\right)^2-16x^2=\left(x^2-4x+8\right)\left(x^2+4x+8\right)\\ c,=x^8+x^7+x^6-x^6+x^5-x^5+x^4-x^4+x^3-x^3+x^2-x^2+x-x+1\\ =x^6\left(x^2+x+1\right)-x^4\left(x^2+x+1\right)+x^3\left(x^2+x+1\right)-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\\ =\left(x^6-x^4+x^3-x+1\right)\left(x^2+x+1\right)\)

\(d,=x^8+2x^4+1-x^4=\left(x^4+1\right)^2-x^4=\left(x^4-x^2+1\right)\left(x^4+x^2+1\right)\\ =\left(x^4-x^2+1\right)\left(x^4+2x^2+1-x^2\right)\\ =\left(x^4-x^2+1\right)\left(x^2-x+1\right)\left(x^2+x+1\right)\\ e,=x^5+x^4-x^4+x^3-x^3+x^2-x^2+x+1\\ =x^3\left(x^2+x+1\right)-x^2\left(x^2+x+x\right)+\left(x^2+x+1\right)\\ =\left(x^3-x^2+1\right)\left(x^2+x+1\right)\\ f,=x^3+2x^2-x^2-2x+2x+4\\ =\left(x+2\right)\left(x^2-x+2\right)\\ g,=x^4+2x^2+1-25=\left(x^2+1\right)^2-25\\ =\left(x^2+1-5\right)\left(x^2-1-5\right)=\left(x^2-4\right)\left(x^2-6\right)=\left(x-2\right)\left(x+2\right)\left(x^2-6\right)\)

\(h,=x^3-2x^2+2x^2-4x+2x-4=\left(x-2\right)\left(x^2+2x+2\right)\\ i,=a^4-4a^2b^2+4b^4-4a^2b^2=\left(a^2-2b^2\right)^2-4a^2b^2\\ =\left(a^2-2ab-2b^2\right)\left(a^2+2ab-2b^2\right)\)

a, Ta có phương trình cân bằng nhiệt

\(Q_{toả}=Q_{thu}\\ \Leftrightarrow2.380\left(150-t_{cb}\right)=1,5.4200\left(t_{cb}-30\right)\\ \Rightarrow t_{cb}=42,91^o\) 

b, Theo đề bài ta đc

( đoạn này mik chưa hiểu đề lắm nói rõ ra đc ko bạn )

Mình viết phần điền tiếp thui nhé, cái đề cho mk k viết

1 where they were organizing the party

2 if I knew the woman in red over there

3 Peter why he didn't turn off the light

4 she was going

5 if the nearest post office was far away

6 what we were going to do that Christmas

7 where I worked

8 how far it was from my house to my school

9 if his friend was a good person

10 how many people there were in my family

1. ...where they were organizing the party.

2. ...if I knew the woman in red over there.

3. ...Peter why he didn't turn off the light.

4. ...she was going.

5. ...if the nearest post office was far away.

6. ...what we were going to do this Christmas.

7. ...where I worked.

8. ...how far it was from my house to my school.

9. ...if his friend was a good person.

10. ...how many people there were in my family.

1. ...where they were organizing the party.

2. ...if I knew the woman in red over there.

3. ...Peter why he didn't turn off the light.

4. ...she was going.

5. ...if the nearest post office was far away.

6. ...what we were going to do this Christmas.

7. ...where I worked.

8. ...how far it was from my house to my school.

9. ...if his friend was a good person.

10. ...how many people there were in my family.

a: Xét tứ giác BHCK có 

BK//CH

BH//CK

Do đó:BHCK là hình bình hành

cảm mơn ạ do máy e bị nhảy chữ cho e xin lỗi ạ