Hong chép mạng nha

= -0,166666666667

    - \(\dfrac{4}{27}\) - \(\dfrac{7}{12}\) - \(\dfrac{23}{27}\) + \(\dfrac{17}{12}\)

=  - (\(\dfrac{4}{27}\) + \(\dfrac{23}{27}\)) + (\(\dfrac{17}{12}\)  - \(\dfrac{7}{12}\))

= - \(\dfrac{27}{27}\) + \(\dfrac{10}{12}\)

= -1 + \(\dfrac{5}{6}\)

=  - \(\dfrac{6}{6}\) + \(\dfrac{5}{6}\)

= - \(\dfrac{1}{6}\)

Bài 7:

Vì $Cx\parallel AB$ nên:

$\widehat{C_1}=\widehat{BAC}$ (2 góc so le trong) 

$=180^0-\widehat{ABC}-\widehat{ACB}=180^0-75^0-30^0=75^0$ 

$\widehat{C_2}=180^0-\widehat{ACB}-\widehat{C_1}$

$=180^0-30^0-75^0=75^0$

$\Rightarrow \widehat{C_1}=\widehat{C_2}$

$\Rightarrow Cx$ là tia phân giác của $\widehat{ACy}$

Bài 6:

a. Ta thấy $AB\perp BD, CD\perp BD\Rightarrow AB\parallel CD(1)$

$CD\perp DF, EF\perp DF\Rightarrow CD\parallel EF(2)$
Từ $(1); (2)\Rightarrow AB\parallel CD\parallel EF$ 

b. 

Vì $CD\parallel EF$ nên:

$\widehat{C_1}=\widehat{CEF}=65^0$ (2 góc so le trong) 

$\widehat{C_2}=180^0-\widehat{C_1}=180^0-65^0=115^0$

Hình tự vẽ nhé
Xét △OAD và △OCB, có 
OA=OC (giả thiết)
Góc AOD chung
OD=OB(giả thiết)
=> △OAD=△OCB (cgc)
b) vì △OAD=△OCB
=> AD=BC
lại có: AB = OB-OA
          CD = OD-OC
=> AB=CD
Xét △CAB và △ACD, có
AC cạnh chung
AB=CD
AD=CB
=> △CAB=△ACD

cho tam giác ABC có góc A=80 độ.dựng AH vuông góc với BC(H thuộc BC).Trên ttia đối của tia HA lấy điểm D sao cho HD=HA.   câu a, chứng minh AC=DC    câu b, chứng minh tam giác ABC= tam giác DBC     câu c, TÍNH SỐ ĐO GÓC bdc

cứu tôi với

1.She seems nice/nicely,but hasn't treated some of her friends good/well

2.Her ankle was swollen and painful/painfully.She could hard/hardly move it
3.He got up late/lately,so he had his breakfast quick/quickly and left

4.The tickets are expensive/expensively,but children under five can travel free/freely

5.I haven't been swimming late/lately because i've been busy/busily

6.I left happy/happily because at last i could express myself free/freely

7.He's worked hard/hardly for years and now he's become famous/famously

8.I was angr/angrily with him because he hadn't been completely honest/honestly with me

9.he cut my hair bad/badly,so now it looks horrible/horribly 

\(\dfrac{36^6+6^4}{36^5+36}\)

\(=\dfrac{36^6+\left(6^2\right)^2}{36\cdot\left(36^4+1\right)}\)

\(=\dfrac{36^6+36^2}{36\cdot\left(36^4+1\right)}\)

\(=\dfrac{36^2\cdot\left(36^4+1\right)}{36\cdot\left(36^4+1\right)}\)

\(=36\)

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