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7 tháng 3 2022

help me pls

7 tháng 3 2022

a) Xét \(\Delta BAD:AB=BD\left(gt\right).\Rightarrow\Delta BAD\) cân tại B.

Mà \(\widehat{B}=60^o\left(gt\right).\)

\(\Rightarrow\Delta BAD\) đều.

b) Xét \(\Delta ABI\) và \(\Delta DBI:\)

BI chung.

AB = DB (gt).

\(\widehat{ABI}=\widehat{DBI}\) (BI là phân giác).

\(\Rightarrow\) \(\Delta ABI=\) \(\Delta DBI\left(c-g-c\right).\)

c) \(\Delta ABD\) đều (cmt).

\(\Rightarrow AB=BD=6\left(cm\right).\)

BI là phân giác góc B (gt).

\(\Rightarrow\widehat{IBC}=60^o.\)

Xét \(\Delta ABC\) vuông tại A: \(\widehat{B}=60^o\left(gt\right).\Rightarrow\widehat{C}=30^o.\)

Xét \(\Delta IBC:\widehat{IBC}=I\widehat{CB}\left(=60^o\right).\)

\(\Rightarrow\Delta IBC\) cân tại I.

Mà ID là đường cao \(\left(ID\perp BC\right).\)

\(\Rightarrow\) ID là trung tuyến.

\(\Rightarrow\) D là trung điểm BC.

\(\Rightarrow BC=2BD=2.6=12\left(cm\right).\)

30 tháng 6 2021

1 Yesterday the plane took off earlier than I expected

2 My mother looks after us more carefully than my father

3 They cut the big cake into smaller parts than I thought

4 My sister even tells me off more often than my mother does

5 Who saw you off yesterday?

6 It is cold today so I put on more warm clothes than usual

7 Yesterday my mother picked my up later than usual

8 You are the pretties girl I have ever known

9 Unless you listen attentively to your teacher, you won't catch up with your friends

10 By far, "The Little Prince" has been my favorite book

5 tháng 9 2021

39 be on time for your interview

40 tall is she

41 What is she like?

42 have you been in this city?

43 is the price of those books

44 How did she greet friends?

45 What did she walk to the station for

17 tháng 9 2021

2 is going to b

3 am writing

4 has also typed

5 has been planting

6 has written

7 have just heard

8 does the play start

9 have worked

10 have practise

11 go

19 tháng 9 2021

1 Mary thanked me for looking after her children when she was away

2 The mother warned her son not to play near the dog

3 Tim insisted on taking Laura to the airport

4 Miss Hoa thanked me for inviting her to the dinner

5 He suggested going to the movies

6 The boy denied cheating in the exam

7 chưa có từ gọi ý

19 tháng 9 2021

7 Tracy thanked Mr Smith for helping her

8 Susan refused to come to Jack's birthday party the next Saturday evening

9 She accused Tom of telling a lie

10 She suggested taking part in voluntary club

11 Tom advised Ba to study hard for the coming exam

12 Paul reminded me to buy some bread

13 She asked me why I had turned off the television

14 Peter asked Linda if she had invited those girls to her party the day before

15 Long asked Van if he watched television every evening

16 Kerry told Cheryl she had something to tell him

17 Peter suggested that I ask the teacher for help

18 Ivan promised to play back the money to Gloria

19 Frederic invited Sarah to come to his birthday party

20 He offered me some more beer

21 He suggested going to the cinema that night

22 Jasmine advised me to rest for a few days

a: Ta có: \(P=\left(\dfrac{\sqrt{x}}{\sqrt{x}-2}-\dfrac{x-\sqrt{x}-1}{x-2\sqrt{x}}\right):\left(\dfrac{\sqrt{x}+2}{\sqrt{x}+1}-\dfrac{x-5}{x-\sqrt{x}-2}\right)\)

\(=\dfrac{x-x+\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}-2\right)}:\dfrac{x-4-x+5}{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}\)

\(=\dfrac{\sqrt{x}+1}{\sqrt{x}\left(\sqrt{x}-2\right)}\cdot\dfrac{\left(\sqrt{x}-2\right)\left(\sqrt{x}+1\right)}{1}\)

\(=\dfrac{x+2\sqrt{x}+1}{\sqrt{x}}\)

21 tháng 9 2021

undefined

22 tháng 12 2021

\(=\dfrac{3^5.\left(2^2\right)^3}{2^5.\left(3^2\right)^3}=\dfrac{3^5.2^6}{2^5.3^6}=\dfrac{2}{3}\)

22 tháng 12 2021

\(=\dfrac{3}{2}\)