a: Vì \(NQ=\dfrac{1}{3}NP\)

nên \(S_{MNQ}=\dfrac{1}{3}\cdot S_{MNP}\)

b: Ta có: NQ+QP=NP

=>\(QP=NP-NQ=NP-\dfrac{1}{3}NP=\dfrac{2}{3}NP\)

=>\(QN=\dfrac{1}{2}QP\)

=>\(S_{MNQ}=\dfrac{1}{2}\cdot S_{MQP}\)

1. She goes to school on foot because it is near her house.
2. Although Sally likes flowers very much, she does not have time to water them.
3. What kind of TV programme did Mai like to watch most when she was small?
4. My sister spent last summer traveling the world.
5. Children should be careful with this stove because it is hot.
6. Their apartment has two rooms and it is on the eighth floor of the building.
7. My father often plays chess with me, but sometimes he plays with his friends.
8. My brother is interested in jogging because it is good for his health.
9. Yesterday, I did not go to the movie because I had to stay home to do homework.
10. You should give up smoking because it is not good for your health.
11. Helen wants to buy a new car, but she does not have enough money.
12. I enjoy living in the countryside because it is more peaceful than the city.
13. Mary was surprised when her father gave her a bar of chocolate yesterday.
14. Most people prefer reading comic books to watching cartoons.
15. Jenny lives in Ho Chi Minh city and has a lot of relatives there.
16. John always tries his best to get the highest score in his class.
17. His classmates do not often go swimming on the weekend, but they go sailing.
18. Sam wanted to buy a loaf of bread so she decided to go to the bakery.
19. It is better for him to travel to his office by bus.
20. Many children enjoy playing water sports, but their parents do not allow them.

S_AMC  = \(\dfrac{1}{2}\) S_ABC vì hai tam giác có chung chiều cao và MC = \(\dfrac{1}{2}\) BC

S_ABC  = 2 x S_ABM (vì hai tam giác có chung chiều cao và BC = 2 x BM

Vì KC=1/2KA

nên \(AK=\dfrac{2}{3}AC\)

=>\(S_{ABK}=\dfrac{2}{3}\cdot S_{ABC}=170\left(cm^2\right)\)

Vì \(QB=\dfrac{3}{5}BA\) nên \(AQ=\dfrac{2}{5}AB\)

=>\(S_{AQK}=\dfrac{2}{5}\cdot S_{ABK}=\dfrac{2}{5}\cdot170=68\left(cm^2\right)\)

ta có: \(S_{AQK}+S_{BQKC}=S_{ABC}\)

=>\(S_{BQKC}+68=255\)

=>\(S_{BQKC}=255-68=187\left(cm^2\right)\)

Diện tích cần quét xi măng là:

\(2\times1,5+\left(2+1,5\right)\times2\times2=17\left(m^2\right)\)

Để quét sơn hết bể thì mất:

\(17:1\times14=238\left(p\right)\)

ĐS: ... 

0,5 ngày = 12 giờ

0,5 ngày = 24 giờ x 0,5  = 12 giờ

--> C. Gia truyền
--> D. Truyền ngôi
--> E. Truyền tụng
~~~~~~~~~~~~~~
--> Gia truyền là bí quyết, kỹ thuật, nghề nghiệp được truyền lại trong gia đình từ đời này sang đời khác.
--> Truyền ngôi là trao lại vị trí vua cho người kế vị.
--> Truyền tụng là kể lại, ca ngợi những câu chuyện, sự kiện hay người có công lao.

C, D và E đều có nghĩa là trao lại, truyền lại

Đáy lớn của mảnh đất hình thang là :

15 x \(\dfrac{5}{3}\) = 25 (m)

Chiều cao mảnh đất hình thang là:

(15 + 25) : 2 = 20 (m)

Diện tích mảnh đất hình thang là :

(25 + 15) x 20 : 2 = 400 (m²)

Đổi 400 m² = 0,04 ha

Đáp số : 0,04 ha

65,4 : 0,125 + 65,4 : 0,5

=65,4 x 8 + 65,4 x 2

= 65,4 x (8+2)

=65,4 x 10

= 654

65,4 : 0,125 + 65,4 : 0,5 = 654.

Sai bạn nhé. $\frac{5}{1}=5$ chứ $\frac{5}{1}$ không bằng $\frac{5}{5}$