a, I thuộc đường trung trực của AD (Gt)

=> IA = ID (Đl)

I thuộc đường trung trực của BC (gt)

=> IB = IC (đl)

b, xét ta giác IAB và tam giác IDC có : CD = AB (gt)

IB = IC (câu a)

IA = ID (câu a)

=> tam giác IAB = tam giác IDC (c-c-c)

A C B I D

a) I \(\in\) đường trung trực của BC

\(\Rightarrow IB=IC\)

I \(\in\) đường trung trực của AD

\(\Rightarrow IA=ID\Rightarrow\Delta IAD\) cân \(\Rightarrow\widehat{IAC}=\widehat{IDC}\) ( 1 )

Xét \(\Delta IAB\) và \(\Delta IDC\) có :

\(AB=CD\)

\(IB=IC\)

\(IA=ID\)

\(\Rightarrow\Delta IAB=\Delta IDC\)

\(\Rightarrow\widehat{BAI}=\widehat{CDI}\) ( 2 )

Từ (1) và (2) \(\Rightarrow\widehat{BAI}=\widehat{IAC}\Rightarrow AI\) là phân giác của \(\widehat{BAC}\)

Gọi 2²³+1/2²⁵+1 là A;2²⁵+1/2²⁷+1 là B 

Ta có 2²A=2²⁵+4/2²⁵+1

2²A=2²⁵+1/2²⁵+1 + 3/2²⁵+1    

2²A=1+3/2²⁵+1

Có 2²B=2²⁷+4/2²⁷+1

2²B=2²⁷+1/2²⁷+1 + 3/2²⁷+1

2²B=1+3/2²⁷+1

Vì 1+3/2²⁵+1>1+3/2²⁷+1

nên 2²A>2²B

nên A>B

Vậy A>B

Cảm ơn Pé's Pơ's nhiều nha

I think bicycles are the best transport in Vietnam. It is convenient and good for health. Riding a bicycle, I can develope a strong heart and muscular limbs. Using a bike for transportation also can help you lose weight and improve your overall health. In city or countryside, when you ride bicycle, you don't need to worry about parking problems and can save money on fuel. Morever, bicycles are only means of transport with don't pollute the environment. Those are some reasons why bicycles are the best means of transport in Vietnam.

I think bicycles are the best transport in Vietnam. It is convenient and good for health. Riding a bicycle, I can develope a strong heart and muscular limbs. Using a bike for transportation also can help you lose weight and improve your overall health. In city or countryside, when you ride bicycle, you don't need to worry about parking problems and can save money on fuel. Morever, bicycles are only means of transport with don't pollute the environment. Those are some reasons why bicycles are the best means of transport in Vietnam.
❤☺

OR

I'd a bicycle and I think bicycle is the best means of transport in Vietnam, because if you want to perfectly feel the atmosphere of Vietnam daily life, hire one bicycle and ride around the city in the early morning. in Hanoi, you can see the early morning market, parks in the morning with exercises of local people, Hanoi streets with not many vehicles.

31. I’d better have a shower. I haven't had one since Thursday.
32. I don’t live with my family now and we haven't seen each other for five years.
33. Look! It is raining

My mother is cookingat the  moment.
35. How long did you know each other?
36. Did you take many photographs on your last holiday ?
37.Has she eaten at the Royal Hotel yet ?
38.Does he live here ? 

39. ShevisitedHanoi last year.

40. Mai sometimes goes out with her friends.

1.In 201,51,515 people attended Burning Man. (How many)​​

How many people attend Buring Man in 20115?

2.some youngsters accidentally knocked over one of the giants.(what)

What did some youngsters do ?

3.The highlight of the festival is the tomato fight.(what)

What is the highlight of the festival?

​4. La Tomatina dates back to 1945 when an annual parade of enormous figures with big heads was passing through the streets of Bunyol.(when)

When did La Tomatine date back?

5. La Tomatina in Bunol near Valencia happens every year.(How often)

How often La Tomatina in Bunol near Valencia?

6.La Tomatina takes place on the last Wednesday in August.(when)

When does La Tomatina take place?

7.The festival began in San Francisco's Baker Beach in 1986.(when,where)

When and where did the festival begin?

8.it takes its name from the ritual burning of a large wooden model of a hated person.(what)

What does ti take its name from?

9.Burning Man lasts one week.(How Long)

How long does the Buring Man last?

10.The event begins on the last Monday in August,and ends on the first Monday in September.(when)

When does the event begin?

học tốt

a,Ta có:
 \(AH\perp BC\) nên \(\widehat{AHB}\) +90 độ.
Vì M là tia đối của HA nên \(\widehat{MHB}\)= 90 độ.
Xét \(\Delta ABH\) và \(\Delta MBH\)có
AH = MH (gt)
\(\widehat{AHB}\) = \(\widehat{MHB}\) (= 90 độ )
BH : cạnh chung

\(\Rightarrow\Delta ABH=\Delta MBH\)( c.g.c )

b,Xét \(\Delta AHCv\text{à}\Delta MHC\)Ta có:

AH = HM (gt)

\(\widehat{AHC}\)= \(\widehat{MHC}\)(= 90 độ)

HC : cạnh chung

\(\Rightarrow\Delta AHC=\Delta MHC\)( c.g.c)

\(\Rightarrow\)AC=CM ( t/ứ)

Mà AC = CN (gt) và CM = AC (cmt)

nên CM = CN

\(\Rightarrow\Delta CMN\)cân 

Để A là số nguyên thì 3x+2 \(⋮\)x-3 

-->3(x-3)+5 \(⋮\)x-3 

Vì x-3 thì chia hết cho x-3 nên 3(x-3)\(⋮\)x-3

-->5\(⋮\)x-3

-->x-3 \(\in\)Ư(5)={1,5,-1,-5}

Với x-3=1

       x=1+3

      x=4

Với x-3=5

       x=5+3

      x=8 

Với x-3= -1

      x= -1+3

      x=2

Với x-3= -5

       x= -5+3

       x= -2

 Do x= -2 hoặc x=8 thì phân số A= 3x+2/x-3 ko thuộc Z 

nên x\(\ne\)-2 và x\(\ne\)8

Vậy x thuộc {2;4}

 Nếu mk làm sai thì xin lỗi bn nha

Cảm ơn Cưu dương nha