Ex3:
1. eco-friendly
2. household appliance
3. reduce
4. meet
5. adopt
6. energy
7. organic
8. raise
Ex4:
1. plastic
2. drop
3. organic
4. awareness
5. protect
6. set up
7. household
8. eco-friendly 

Bài 3

1 eco-friendly

2 household appliance

3 reduce

4 meet

5 adopt

6 energy

7 organic

8 raise

1.C
2.A
3.B
4.A
5.C
6.A
7.B
8.A
9.B
10.C
11.C
12.A
13.A
14.B
15.D
16.D
17.C
18.B
19.A
20.A

1 C

2 A

3 B

4 A

5 C

6 A

7 B

8 A

9 B

10 C

a)

Áp dụng ĐL cosin cho \(\Delta ABC\) có:

\(BC^2=AB^2+AC^2-2AB\cdot AC\cdot cos120^o\)

\(BC=\sqrt{3^2+4^2-2\cdot3\cdot4\cdot\left(-\dfrac{1}{2}\right)}=\sqrt{37}\)

b)

Áp dụng hệ quả ĐL cosin cho \(\Delta ABC\) có:

\(cosB=\dfrac{AB^2+BC^2-AC^2}{2\cdot AB\cdot AC}\)

\(cosB=\dfrac{3^2+\sqrt{37}^2-4^2}{2\cdot3\cdot\sqrt{37}}=\dfrac{5\sqrt{37}}{37}\)

\(\Rightarrow\widehat{B}\approx35^o\)

\(\Rightarrow\widehat{C}=180^o-120^o-35^o=25^o\)

c)

\(S_{ABC}=\dfrac{1}{2}AB\cdot AC\cdot sin120^o=\dfrac{1}{2}\cdot3\cdot4\cdot\dfrac{\sqrt{3}}{2}=3\sqrt{3}\) 

???????

PHONETICS
I.
1.A (/e/ ≠ /ɪ/)
2.C (/i:/ ≠ /ju/)
3.D (/y/ ≠ /ɪ/)
4.A (âm 2 còn lại âm 1)
5.B (âm 1 còn lại âm 2)
____________________
1.B
2.E
3.A
4.G
5.C
6.H
7.J
8.I
9.D
10.F

Phonetics

1 A

2 C

3 D

4 A

5 B

Vocab

1 B

2 E

3 A

4 G

5 C

6 H

7 J

8 I

9 D

10 F