Xét tam giác AMB và tam giác AMD, ta có:

c: AB = AD (gt)

g: góc BAM = góc DAM (gt)

c: AM chung

=> Tam giác AMB = Tam giác AMD (c.g.c)

=> góc ABM = góc ADM (2 góc tương ứng)

BM = MD (2 cạnh tương ứng)

Có góc ABM + góc MBH = 180 độ (kề bù)

góc ADM + góc MDC = 180 độ (kề bù)

=> góc MBH = góc MDC

Xét tam giác MBH và tam giác MDC, ta có:

g: góc MBH = góc MDC (cmt)

c: BM = MD (cmt)

g: góc BMH = góc DMC (đối đỉnh)

=> tam giác MBH = tam giác MDC (g.c.g)

=> BH = DC (2 cạnh tương ứng)

Mà AB = AD (gt)

=> AH = AC

=> tam giác AHC cân tại A (đpcm)

a) Ví dụ:

- Người đàn ông đẩy chiếc ô tô chết máy (người đàn ông tác dụng lực đẩy lên chiếc ô tô chết máy)

- Cậu bé kéo chiếc xe cút kít (cậu bé tác dụng lực kéo lên chiếc xe cút kít)

b)

a) Ví dụ:

- Người đàn ông đẩy chiếc ô tô chết máy (người đàn ông tác dụng lực đẩy lên chiếc ô tô chết máy)

- Cậu bé kéo chiếc xe cút kít (cậu bé tác dụng lực kéo lên chiếc xe cút kít)

b)

Question 1: Robots can work as guards in important places.

Question 2: Hanoi is famous for its delicious street food.

Question 3: What type of house will you live in in the future?

Question 4: Pack your lunch in a lunchbox instead of packing it in a plastic bag.

Question 1: Robots can work as guards in important places.

Question 2: Hanoi is famous for its delicious street food.

Question 3: What type of house will you live in in the future?

Question 4: Pack your lunch in a lunchbox instead of packing it in a plastic bag.

a) \(\dfrac{-5}{9}\) + \(\dfrac{8}{15}\) + \(\dfrac{-2}{11}\) + \(\dfrac{4}{-9}\) + \(\dfrac{7}{15}\)

= \(\dfrac{-5}{9}\) + \(\dfrac{8}{15}\) + \(\dfrac{-2}{11}\) + \(\dfrac{-4}{9}\) + \(\dfrac{7}{15}\)

= \(\left(\dfrac{-5}{9}+\dfrac{-4}{9}\right)\) + \(\left(\dfrac{8}{15}+\dfrac{7}{15}\right)\) + \(\dfrac{-2}{11}\)

= -1 + 1 + \(\dfrac{-2}{11}\)

= 0 + \(\dfrac{-2}{11}\)

= \(\dfrac{-2}{11}\)

b) \(\left(\dfrac{7}{2}.\dfrac{5}{6}\right)\) + (\(\dfrac{7}{6}.\dfrac{7}{2}\))

= \(\dfrac{7}{2}.\dfrac{5}{6}\) + \(\dfrac{7}{6}.\dfrac{7}{2}\)

=7

Ta thấy: \(\dfrac{5}{-12}\) = \(\dfrac{-5}{12}\)

Vì BCNN (8, 12) = 24 nên ta có:

\(\dfrac{-3}{8}\) = \(\dfrac{-3.3}{8.3}\) = \(\dfrac{-9}{24}\)

\(\dfrac{-5}{12}\) = \(\dfrac{-5.2}{12.2}\) = \(\dfrac{-10}{24}\)

Mà -9 > -10 nên \(\dfrac{-9}{24}\) > \(\dfrac{-10}{24}\). Vậy \(\dfrac{-3}{8}\) > \(\dfrac{5}{-12}\)

b) Ta có:

\(\dfrac{3131}{5252}\) = \(\dfrac{3131:101}{5252:101}\) = \(\dfrac{31}{52}\)

Mà \(\dfrac{31}{52}\) = \(\dfrac{31}{52}\) nên \(\dfrac{3131}{5252}\) = \(\dfrac{31}{52}\)

Question 6: Who wants to be a millionaire? is on at eight o’clock every Tuesday night.

Question 7: Could you turn up the volume please? I can’t hear that singer very well.

Question 8: I like watching the news because I want to know what is happening around the world.

Question 9: The film was boring, so I felt asleep in the middle.

Question 10: I want to buy that new jacket but I don’t have enough money. Question 11: Documentary is a programme about important events. Question 12: Grandma watches her favourite series every day. She never misses any episodes. Question 13: Jill Newman is a/(an) newsreader on News at Ten.

I live in the capital city in Vietnam - Hanoi. There are many things I like about my neighbourhood, like sunny wether, helpful and friendly people. As you can see, there are also a lot of shops and markets, and they are very convienent for me to go shopping for just 5 minutes. However, there are some things I dislike about it. The air is very clean and the streets are always crowded. But, I'm sure my favourite city is still Hanoi.

Dear Mai,

My neighbourhood is in Hanoi. In Hanoi, I can see a lot of shops, museums and theater. It's really crowded and busy. Everyday, there are lots of traffics that cause traffic jams. The air is so polluted, not like in my countryside so I don't want to live in Hanoi very much. How about you? What's your neighbourhood like?

Thi

Tran Phuc Giang Thi