1+1=2 ok bn lì

1+1=2

Bạn bị rảnh háng ak??

Ta có: IJ−→=IA−→+AB−→−+BJ−→IJ→=IA→+AB→+BJ→
IJ−→=ID−→+DC−→−+CJ−→IJ→=ID→+DC→+CJ→
⇒IJ−→=12(AB−→−+DC−→−)⇒IJ→=12(AB→+DC→)
Xét:
HK−→−.IJ→=12(OK−→−−OH−→−).(AB−→−+DC−→−)=12(OK−→−.AB−→−+OK−→−.DC−→−−OH−→−.AB−→−−OH−→−.DC−→−)=12(OK−→−.AB−→−−OH−→−.DC−→−)=12[(OC−→−+CK−→−).(OB−→−−OA−→−)−(OA−→−+AH−→−).(OC−→−−OD−→−)]=12[(OB−→−−OA−→−−AH−→−).OC−→−−(CK−→−+OC−→−−OD−→−).OA−→−]=12[(HA−→−+AO−→−+OB−→−).OC−→−−(DO−→−+OC−→−+CK−→−).OA−→−]=12(HB−→−.OC−→−−DK−→−.OA−→−)=0⇔HK⊥IJ

 1. How much..is.....that poster ?

  2. ..Are...you play the guitar ?

  3. It's ......a book

  4. I don't ...watch...TV

  5. It ..is....0912789580

 6. The house is....verry....big

 7 I..am....live in Hanoi

 8. I.don't... coffee, thanks

2) Do

4) watching

6) a

7) am

8) am

(sai thì thôi)

#Học tốt!!!

~NTTH~

\(a)=-56\)

\(b)=30\)

\(c)=-48\)

\(d)=\frac{8}{100}\times900=8\times9=72\)

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HỌC TỐT NHÉ 

My name is ... . I am a stundent . My family has five . My father is a smile .My mother is a teacher . She works at Quang Trung school . My sister is a engineer and brother is a electrician .