qua bong , cai bong

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thật ra bài này đáp án là 35 học sinh 

Chúc mừng các bạn

chúng mày ngu khó nó mới hỏi mà khó thiệt đó

sai rui dap an phai la 7611 chu

kho 

10 bạn

Bài này mình làm được thầy chấm 9 điểm, bạn đọc tham khảo nha

Volunteer is one of Vietnam’s long-standing activities contributing effectively to community development, capacity building and poverty reduction. Volunteer activities are taking place vibrantly with every passing day, not only do they bring positive results from specific volunteer programs but they also conduce to generate and raise awareness for a large number of people in Vietnam.The key point of volunteer activities is a part of a global effort to ensure that every child has access to a quality education – it’s a direct route out of poverty. In addition, the activities will be the main distributor of connecting the people, improving the living standard, and helping the poor around countries.However, the volunteer activities of Vietnam are very diverse in both content and form. In fact, these volunteer activities remain separate and spontaneous; information on volunteer activities is not accessible with majority seeking information about specific volunteer programs that interest them due to the lack of coordinating network among volunteer clubs and organizations.With a tradition of solidarity and compassion, all Vietnamese people profoundly understand that, to rise from a low starting point, each individual has to make every effort to promote internal strength by volunteering to help the needy and contribute to the development of communities and country.

G - O - O - D L - U - C - K !

Ta có : \(\widehat{B}=\widehat{ACB}\) ( \(\Delta\) cân tại A )

==> \(\widehat{ACB}=75\) độ

Tam giác HCB vuông tại H có: \(\widehat{B}+\widehat{HCB}=90\) độ

75 + \(\widehat{HCB}\) = 90 độ

\(\widehat{HCB}\) = 15 độ

Mà \(\widehat{ACB}=\widehat{HCB}+\widehat{ECD}\)

75 = 15 + \(\widehat{ECD}\)

==> \(\widehat{ECD}\) = 60độ

Tam giác AHC có: \(\widehat{H}=90\) độ (gt)

\(\widehat{ECD=}60\) độ (cmt)

==> Tam giác AHC là nửa tam giác đều.

==> 2CH = AC

Mà AC = AB ( \(\Delta\) ABC cân tại A )

==> 2CH = AB hay \(CH=\dfrac{AB}{2}\) (đpcm)

Nếu còn gì thắc mắc thì vào phần bình luận nhé!

CHÚC BẠN HỌC TỐT ***

Ta có: Tử là:

B=\(\frac{1}{2013}+\frac{2}{2012}+...+\frac{2012}{2}+\left(1+1+...+1\right)\)            (2013 số hạng 1)

   =\(\left(\frac{1}{2013}+1\right)+\left(\frac{2}{2012}+1\right)+...+\left(\frac{2012}{2}+1\right)+\left(1\right)\)

  =\(\frac{2014}{2013}+\frac{2014}{2012}+...+\frac{2014}{2}+\frac{2014}{2014}\)

 =\(2014\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2013}+\frac{1}{2014}\right)\)

=>A=\(\frac{2014\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2014}\right)}{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2014}}\)=2014