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+ ΔAHB và ΔCKD có
HB = KD (=1)
góc AHB = góc CKD(=90º)
AH = CK (=3).
⇒ ΔAHB = ΔCKD(c.g.c)
⇒AB = CD (hai cạnh tương ứng)
+ ΔCEB và ΔAFD có
BE = DF (=2)
góc BEC = góc DFA (=90º)
CE = AF (=4).
⇒ ΔCEB = ΔAFD ( c.g.c)
⇒ BC = AD (hai cạnh tương ứng)
b) ΔABD và ΔCDB có
AB = CD
AD = BC
BD cạnh chung
⇒ ΔABD = ΔCDB (c.c.c)
⇒ góc ABD = góc CDB (hai góc tương ứng)
Vậy AB // CD ( hai gó so le trong bằng nhau )
k minh nha
(hình hơi xấu, thông cảm nha)
a) Xét \(\Delta AEB\)và \(\Delta DFC\) có:
AE = DF
\(\widehat{AEB}=\widehat{DFC}=90^o\)
BE = CF
Do đó: \(\Delta AEB=\Delta DFC\) (c.g.c)
Suy ra: AB = DC (đpcm)
Xét \(\Delta BMC\) và \(\Delta DNA\) có:
MC = NA
\(\widehat{BMC}=\widehat{DNA}=90^o\)
BM = DN
Do đó: \(\Delta BMC=\Delta DNA\)
Suy ra: BC = AD (đpcm)
b) Xét \(\Delta ABD\) và \(\Delta CDB\) có:
AB = CD (câu a)
BC = AD (câu a)
BD là cạnh chung
Do đó: \(\Delta ABD=\Delta CDB\) (c.c.c)
Suy ra: \(\widehat{ABD}=\widehat{CDB}\) (so le trong)
=> AB // CD (đpcm)
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A.PHONETICS
1.
1. A. animation
2. D. sign
3. C. vehicle
4. D. naked
5. C. wanted
2.
/t/: watched, walked, brushed, washed, danced
/d/: amazed, terrified, cleaned, bored, lived
/id/: acted, needed, waited, departed, disappointed
B. VOCABULARY & GRAMMAR
1.
1. A. cinema
2. D. audience
3. A. frightening
4. D. animation
5. C. feeling
2.
1. D. animation
2. C. action
3. D. boring
4. B. surprised
3.
1. C. Although
2. A. Although
3. C. Although
4. B. in spite of
5. D. Despite
6. D. exciting
7. B. terrified
8. A. characters
9. C. boring
10. C. interested
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1. into
2. to
3. at
4. on - in
5. with
6. to
7. above
8. with - for
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1 leaving
2 was sitting
3 am
4 has been giving
5 getting
6 had smoked
7 drink
8 be
9 was
10 haven't finished
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If only your sister could come as well
It looked as if the house had been occupied for several months
He was too tired to stay awake until the end of the film
I was the last person to know about the accident
It’s very important to keep the environment clean
If he had been informed, he would have attended the seminar
In spite of being short of money, I’ll lend you some
I warned the boys not to swim out too far
If she hadn’t forgotten to add salt, the food wouldn’t have been tasteless
If only you had told me earlier
tất cả các bạn kết bạn mình zi