1 A

2 Sai đề

3 A

4 D

5 D

6 A

7 B

8 B

9 D

10 D

11 D

12 C

13 B

14 D

15 C

16 D

17 A

18 C

19 B

20 B

1. A

3. A

4. D

5. D

6. A

7. B

8. B

1 eat less candy

2 Exercise more

3 eat more vegetable

4 use less TV

5 sleep more

6 eat more fish

7 eat less fast food

8 Try talking less

9 drink more warm water

10 sunbathe less

a. \(0< a< 90^0\Rightarrow cosa>0\)

\(cosa=\sqrt{1-sin^2a}=\dfrac{5}{13}\)

\(sin2a=2sina.cosa=\dfrac{120}{169}\)

\(cos2a=2cos^2a-1=2.\left(\dfrac{5}{13}\right)^2-1=-\dfrac{119}{169}\)

b.

\(\dfrac{3\pi}{2}< a< 2\pi\Rightarrow sina< 0\) \(\Rightarrow sina=-\sqrt{1-cos^2a}=-\dfrac{\sqrt{15}}{8}\)

\(sin2a=2sina.cosa=-\dfrac{7\sqrt{15}}{32}\)

\(cos2a=2cos^2a-1=2\left(\dfrac{7}{8}\right)^2-1=\dfrac{17}{32}\)

c.

\(\dfrac{\pi}{2}< a< \pi\Rightarrow sina>0\)

\(\Rightarrow sina=\sqrt{1-cos^2a}=\dfrac{\sqrt{2}}{2}\)

\(sin2a=2sina.cosa=-1\)

\(cos2a=2cos^2a-1=0\)

d.

\(\pi< a< \dfrac{3\pi}{2}\Rightarrow cosa< 0\)

\(\Rightarrow cosa=-\sqrt{1-sin^2a}=-\dfrac{1}{2}\)

\(sin2a=2sina.cosa=\dfrac{\sqrt{3}}{2}\)

\(cos2a=2cos^2a-1=-\dfrac{1}{2}\)

bạn có thể đăng lại câu hỏi không ạ :))

1 more expensive than

2 faster than

3 more modern than

4 hotter than

5 more beautiful than

6 cheaper than

7 better than

8 more convenient than

V

1 the longest

2 the most interesting

3 the biggest

4 the best

5 the most beautiful

6 the coldest

7 the fastest

8 the most important

III

1 height

2 smallest

3 youngest

4 more quiet

5 best

6 take - is raining

7 colder

IX

1 careful

2 activity

3 ninth

4 physical 

5 better

6 interesting

7 employees

8 twentieth

9 teachers

10 once

III

1 height 

2 healthy

3 long

4 sickness

5 unpleasant

6 appointment

VII

1 biggest

2 warmer - hottest

3 best

4 longest

5 noisier

VIII

1 taller

2 better

3 more expensive

4 faster

5 heavier

6 thinner

7 slower

8 cleverere

9 older

10 cheaper

11 taller

12 easier

\(sin\left(\dfrac{\pi}{2}-x\right)+cot^2x=cosx+\dfrac{cos^2x}{sin^2x}=cosx+\dfrac{cos^2x}{1-cos^2x}=a+\dfrac{a^2}{1-a^2}\)

\(=\dfrac{-a^3+a^2+a}{1-a^2}\)

\(\Rightarrow\left\{{}\begin{matrix}m=-1\\n=1\\\end{matrix}\right.\) \(\Rightarrow P=-3\)