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Xét ΔAMN vuông tại A có 

\(MN^2=AM^2+AN^2\)

hay MN=20(cm)

Xét ΔABC có MN//BC

nên MN/BC=AM/AB=2/3

=>20/BC=2/3

hay y=30(cm)

20 tháng 11 2021

1. How many kilos of potatoes would you like?

2. I went fishing but I didn't catch any fish.

3. Cook the chicken over low heat for 15 minutes before you serve it.

4. Can you tell me how to cook broken rice?

5. There are three cartons of milk in the fridge.

6. He has an egg but he hasn't got any bread.

7. Pho is one of the most popular dishes in Vietnam.

16 tháng 9 2021

1) \(\left(\dfrac{-13}{17}-\dfrac{31}{52}\right)-\left(\dfrac{73}{52}-\dfrac{13}{17}+\dfrac{5}{6}\right)-\dfrac{3}{4}\)

\(=\dfrac{-13}{17}-\dfrac{31}{52}-\dfrac{73}{52}+\dfrac{13}{17}-\dfrac{5}{6}-\dfrac{3}{4}\)

\(=\left(\dfrac{-13}{17}+\dfrac{13}{17}\right)-\left(\dfrac{31}{52}+\dfrac{73}{52}\right)-\left(\dfrac{5}{6}+\dfrac{3}{4}\right)\)

\(=0-2-\dfrac{19}{12}\)

\(=-2-\dfrac{19}{12}\)

\(=\dfrac{-43}{12}\)

16 tháng 9 2021

2) \(\dfrac{1}{7}.\dfrac{1}{3}+\dfrac{1}{7}.\dfrac{1}{2}-\dfrac{1}{7}\)

\(=\dfrac{1}{7}\left(\dfrac{1}{3}+\dfrac{1}{2}-1\right)\)

\(=\dfrac{1}{7}.-\dfrac{1}{6}\)

\(=-\dfrac{1}{42}\)

17 tháng 4 2021

V Transformation

1 In spite being quite poor, the villagers live a happy and healthy way

2 Despite studying very hard, he still didn't pass the exam

3 Although Sylvia had no interest in folklore, she still enjoyed the story

4 Despite having much experience in machinery, he didn't succeed in repairing this machine

5 Though it was dark, they continued to work

6 In spite of having health problems, he is always smiling

7 Despite the difficult exam, Kieu Anh got good marks

8 THe man about whom I told you works in the hospital

9 Do you know the girl to whom Tom is talking?

10 The tree which stankds near the gate of my house has lovely flowers

17 tháng 4 2021

11 The book which I was reading yesterday was a lovely story

12 Do you know the new student whose name I can't remember?

13 I will never forget the day when I first met her

14 The country where I was born is beautiful

15 Because of the polluted water, it was unsafe to drink

16 Because he work hard and methodically, John succeeded in his exam

17 I suggest getting together and talking about our presentation before we do it in class

18 When did you built this stilt house?

19 If you don't hurry up, you will be late for school

20 You must turn off the TV before 11p.m

6 tháng 8 2021

b) `sin^2 3x=1`

`<=> (1-cos6x)/2=1`

`<=> 1-cos6x=2`

`<=> cos6x=-1`

`<=> 6x=π +k2π`

`<=>x=π/6 +k π/3 ( k \in ZZ)`

c) `tan^2 2x=3`

`<=> (1-cos4x)/(1+cos4x)=3`

`<=> 1-cos4x=3+3cos4x`

`<=>cos4x = -1/2`

`<=>4x= \pm (2π)/3 +k2π`

`<=>x =  \pm π/6 + k π/2 (k \in ZZ)`

12 tháng 3 2023

mở bài là giới thiệu về cụ nha mn em viết lộn ạ 

thân bài là đóng góp ạ