GT: \(\text{(O;R)}\cap\text{(O';r)}\) lần lượt tại A;B| O;O'\(\in\) 2 nửa mặt phẳng bờ AB. Vẽ cát tuyến PAQ\(\left(P\in\left(O\right);Q\in\left(O'\right)\right)\)
KL: Khi nào A nằm giữa P;Q
Hộ mik vs nha. Thanks nhiều!
Viết PTPƯ hoàn thành chuỗi PƯ
P->P2O5->H3PO4->H2->H2O->O2->Fe3O4->Fe+H2->Cu->CuO
ai giúp tui vs
4P + 5O2 => 2P2O5
P2O5 + 3H2O => 2H3PO4
2H3PO4 + 3Zn => Zn3(PO4)2 + 3H2
H2 + 1/2 O2 => H2O
2H2O => 2H2 + O2
2O2 + 3Fe => Fe3O4
Fe3O4 + 4CO => 3Fe + 4CO2
Fe + 2HCl => FeCl2 + H2
H2 + CuO => Cu + H2O
Cu + 1/2 O2 => CuO
Tìm số nguyên tố xy (x>y>o) sao cho xy - yx là số chính phương.
Tìm số nguyên tố ab biết (a>b>o) sao cho ab - ba là số chính phương
Bài 8 Dat cau hoi cho phan bi gach chan o moi cau sau
1 She is cooking meal in thẻ kichen
->.....................................................................................................................
2: I'd like some milk and vergetables .
->....................................................................................................
3 Miss Nga í teaching English at a secondary shool .
-> ....................................................................................
4 : Nam never files a kite
->....................................................................................................
5: I have a Math and Siên on Monday and Thursday
->...............................................................................
6 He goes to the cinema once a week
->..........................................................................................................................................
7: My sister is in grade 6
-> ......................................................................................................................................................
8: Mai always há dinner at seven o'clock
->....................................................................................................................................
9: My brother wants a glass of lemon juice
->..............................................................................................................................................
10: Linh has milk and eggs for her breakfast
->......................................................................................................
1.What is she doing in the kitchen?
2.What would you ?
3.What's Miss Nga do?
4.Is Nam often flies a kite?
5.What lessons do you have on Monday and Saturday?
6.How often is he go to the cinema?
7.What grade is your sister in?
8.What time does Mai have dinner?
9.What is your brother would?
10.What does Linh have for her breakfast
Dat cau hoi cho phan bi gach chan o moi cau sau
1 She is cooking meal in thẻ kichen
->..................What is she doing in the kichen?.....................................................
2: I'd some milk and vergetables .
->.....................What would you ?..................................
Bài 1: Tính gt biểu thức: \(cos^220^o+cos^240^o+cos^250^o+cos^270^o\)
Bài 2:Chứng minh hệ thức:
a,\(cot^2\text{α}-cos^2\text{α}=cot^2\text{α}.cos^2\text{α}\)
b,\(\dfrac{1+cos\text{ α}}{sin\text{ α}}=\dfrac{sin\text{ α}}{1-cos\text{ α}}\)
(P/s: tại mik ko tìm đc kí hiệu Anpha nên phải viết chữ =.=)
Các bạn giúp mik vs, mik đang cần gấp ak.Mik cảm ơn!!!!
bài 1: ta có : \(cos^220+cos^240+cos^250+cos^270\)
\(=cos^220+cos^270+cos^240+cos^250\)
\(=cos^220+cos^2\left(90-20\right)+cos^240+cos^2\left(90-40\right)\)
\(=cos^220+sin^220+cos^240+sin^240=1+1=2\)
bài 2: a) ta có : \(cot^2\alpha-cos^2\alpha=cos^2\alpha\left(\dfrac{1}{sin^2\alpha}-1\right)=cos^2\alpha.\left(\dfrac{1-sin^2\alpha}{sin^2\alpha}\right)\)
\(=cos^2\alpha.\left(\dfrac{cos^2\alpha}{sin^2\alpha}\right)=cos^2\alpha.cot^2\alpha\left(đpcm\right)\)
b) ta có : \(sin^2\alpha+cos^2\alpha=1\Leftrightarrow sin^2\alpha=1-cos^2\alpha\)
\(\Leftrightarrow sin^2\alpha=\left(1-cos\alpha\right)\left(1+cos\alpha\right)\Leftrightarrow\dfrac{1+cos\alpha}{sin\alpha}=\dfrac{sin\alpha}{1-cos\alpha}\left(đpcm\right)\)
IV. Viết lại các câu sau sao cho nghĩa không đổi:
1. Her old house is bigger than her new one.
=> Her new house...................................................
2. No one in my class is taller than Peter.
=> Peter.......................................................
3. The black dress is more expensive than the white one.
=> The white dress...................................................
4. According to me, English is easier than Maths.
=> According to me, Maths........................................
5. No one in my group is more intelligent than Mary.
=> Mary................................................................
6. No river in the world is longer than the Nile.
=> The Nile...........................................................
7. Mount Everest is the highest mountain in the world.
=> No mountain......................................................
8. This is the first time I have ever met such a pretty girl.
=> She is..............................................................
9. He works much. He feels tired.
=> The more.........................................................
10. This computer works better than that one.
=> That computer.....................................................
11. The apartment is big. The rent is high.
=> The bigger..........................................................
12. We set off soon. We will arrive soon.
=> The sooner............................................................
13. The joke is good. The laughter is loud.
=> The better...............................................................
14. She gets fat. She feels tired.
=> The fatter................................................................
15. As he gets older, he wants to travel less.
=> The older................................................................
16. The children are excited with the difficult games.
=> The more................................................................
17. People dive fast. Many accidents happen.
=> The faster................................................................
18. I meet him much. I hate him much
=> The more................................................................
19. My boss works better when he is pressed for time,
=> The less...................................................................
20. As he has much money, he wants to spend much.
=> The more...................................................................
21. If you read many books, you will have much knowledge.
=> The more.....................................................................
22. He speaks too much and people feel bored.
=> The more.....................................................................
23. The growth in the economy makes people's living condition better.
=> The more.......................................................................
24. People learn a lot of things as they travel far.
=> The farther......................................................................
IV. Viết lại các câu sau sao cho nghĩa không đổi:
1. Her old house is bigger than her new one.
=> Her new house..is smaller than her old one.
2. No one in my class is taller than Peter.
=> Peter..is the tallest student in my class.
3. The black dress is more expensive than the white one.
=> The white dress.....cheaper than the black one.
4. According to me, English is easier than Maths.
=> According to me, Maths....is more difficult than English.
5. No one in my group is more intelligent than Mary.
=> Mary....is the most intelligent person in my group.
6. No river in the world is longer than the Nile.
=> The Nile.....is the longest river in the world.
7. Mount Everest is the highest mountain in the world.
=> No mountain....in the world is higher than Mount Everest.
8. This is the first time I have ever met such a pretty girl.
=> She is..the prettiest girl I have ever met.
9. He works much. He feels tired.
=> The more...she works, the more she feels tired.
10. This computer works better than that one.
=> That computer...works worse than this one.
11. The apartment is big. The rent is high.
=> The bigger......the apartment is, the high the rent is.
12. We set off soon. We will arrive soon.
=> The sooner.......we set off, the sooner we will arrive.
Cho hình vẽ sau, biết a//b; và M1ˆ+2N1ˆ=245độ.Tính M2^và N2ˆ
Theo đề bài ta có: \(\widehat{M_1}+2\widehat{N_1}=245^o\left(1\right)\)
Mà \(\widehat{M_1}+\widehat{N_1}=180^o\) (2 góc trong cùng phía của a//b) (2)
Lấy (1) trừ (2) ta có:
\(\left(\widehat{M_1}+2\widehat{N_1}\right)-\left(\widehat{M_1}+\widehat{N_1}\right)=245^o-180^o\)
\(\Rightarrow\widehat{M_1}+2\widehat{N_1}-\widehat{M_1}-\widehat{N_1}=65^o\)
\(\Rightarrow\widehat{N_1}=65^o\)
Thay \(\widehat{N_1}=65^o\) vào (2) ta có:
\(\widehat{M_1}+65^o=180^o\)
\(\Rightarrow\widehat{M_1}=180^o-65^o=115^o\)
Ta có:
\(\widehat{N_2}=\widehat{M_1}=115^o\) (2 góc so le trong của a//b)
\(\widehat{M_2}=\widehat{N_1}=65^o\) (2 góc so le trong của a//b)
Vậy \(\widehat{N_2}=115^o;\widehat{M_2}=65^o\)
tam giác ABC có góc B>góc C, phân giác ngoài góc A cắt BC tại E. Biết góc A=60o, AEB=15o.Số đo góc ABC = ?
tim abc (a>b>c>0) sao cho :abc +bca + cab =666