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\(a,\widehat{aOn}+\widehat{mOn}+\widehat{mOb}=180^o\left(kề.bù\right)\\ \Leftrightarrow70^o+\widehat{mOn}+40^o=180^o\\ Vậy:\widehat{mOn}=180^o-\left(70^o+40^o\right)=70^o\\ b,Vì:\widehat{aOn}=\widehat{mOn}\\ Mà.tia.On.nằm.giữa.2.tia.Oa.và.Om.nên:\\ On.là.tia.phân.giác.góc.\widehat{aOm}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
AF=FG=GC
=>AG=2/3AC
=>S ABG=2/3*S ABC
BE=ED=1/2AD
=>BE+ED=1/2AD+1/2AD=AD
=>BD=DA
=>D là trung điểm của AB
=>AD=1/2AB
=>BE=ED=1/4AB
AE=AD+DE=1/4AB+1/2AB=3/4AB
=>S AEG=3/4*S ABG=3/4*2/3*S ABC=1/2*S ABC
=>S BEGC=1/2*S ABC
AF=FG
=>AF=1/2*AG
=>S AEF=1/2*S AEG=1/2*1/2*S ABC=1/4*S ABC
AD=2DE
=>AD=2/3AE
=>S ADF=2/3*S AEF=2/3*1/4*S ABC=1/6*S ABC
=>s EDFG=S ABC(1/4-1/6)=1/12*S ABC
S BCGE-S DEFG=15cm2
=>S ABC(1/2-1/12)=15
=>SABC=15:5/12=36cm2
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1. seeing
2. working
3. to meet
4. talking/ to finish
5. asking
6. not to speak
7. carrying
8. overhearing
9. writing/ waiting
10. to avoid/ being
11. giving/ to speak
12. going/ saying
13. to persuade/ to agree
14. sneezing/ sitting
15. driving/ being
16. to start/ looking
17. to show/ to use
18. making/ to do
19. remaining/ to help/ to stay
20. listening/ hearing
21. camping
22. to be
23. to speak
24. to pay
25. to meet
26. not trying/ to solve
27. being
28. hunting
29. to be
30. working
31. going
32. to do
33. to bring
34. working
35. to buy
36. to inform
37. studying
38. to buy
39. to be fed
40. working
![](https://rs.olm.vn/images/avt/0.png?1311)
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\(Bài.7:\\ a,\dfrac{\left(-3\right)^{10}.15^5}{25^3.\left(-9\right)^7}=\dfrac{3^{10}.3^5.5^5}{\left(5^2\right)^3.\left(3^2\right)^6.3.\left(-3\right)}\\ =\dfrac{3^{15}.5^5}{-5^6.3^{14}}=-\dfrac{3}{5}\\ b,2^3+3.\left(\dfrac{1}{9}\right)^0-2^{-2}.4+\left[\left(-2\right)^2:\dfrac{1}{2}\right].8\\ =8+3.1-\dfrac{1}{4}.4+\left[4:\dfrac{1}{2}\right].8\\ =8+3-1+8.8\\ =11-1+64=10+64=74\)
Bài 10:
\(a,3^{35}=\left(3^7\right)^5=2187^5\\ 5^{20}=\left(5^4\right)^5=625^5\\ Vì:2187^5>625^5\left(Vì:2187>625\right)\\ \Rightarrow3^{35}>5^{20}\\ b,2^{32}=\left(2^4\right)^8=16^8\\ Vì:37^8>16^8\left(Do:37>16\right)\\ \Rightarrow37^8>2^{32}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
1 have just seen
2 have ever seen /isdefinitely
3 never use
4 has already seen
5 can probably get
1. D
2. A
3. A
4. B
5. D