Ta có: 

Nếu bóng của hai cột đèn bằng nhau, tức là BC = EF

Suy ra, ABC = DEF (g.c.g)

Từ đó ta có AB = DE (hai cạnh tương ứng)

Vậy khi bóng của hai cột đèn bằng nhau thì độ dài hai cột bằng nhau

a: 

b: Năm 2016 có nhiều vụ nhất

c: SỐ vụ năm 2019 so với năm 2018 đã giảm đi:

$\genfrac{}{}{0ex}{}{18736-17621}{18736}\simeq 5,95\%$

d: Số vụ năm 2020 so với năm 2019 đã giảm đi:

$\genfrac{}{}{0ex}{}{17621-14510}{17621}\simeq 17,66\%$

a/ Ta có

tg ABC cân tại A $\Rightarrow \widehat{ABC}=\widehat{ACB}$ (góc ở đáy tg cân) (1)

$\widehat{ABC}+\widehat{ABD}=\widehat{DBC}=180^o$ (2)

$\widehat{ACB}+\widehat{ACE}=\widehat{BCE}=180^o$ (3)

Từ (1) (2) (3) $\Rightarrow \widehat{ABD}=\widehat{ACE}$

b/

Xét tg ABD và tg ACE có

AB=AC (cạnh bên tg cân ABC)

$\widehat{ABD}=\widehat{ACE}$ (cmt)

BD=CE (gt)

=> tg ABD = tg ACE (c.g.c) => AD=AE => tg ADE là tg cân

Xét tg ABC có

$\widehat{BAC}=180^o-\widehat{ABC}-\widehat{ACB}$ (tổng các góc trong của 1 tg $=180^o$ )

$\Rightarrow \widehat{BAC}=180^o-70^o-30^o=80^o=\widehat{ACD}$

Hai góc $\widehat{BAC}=\widehat{ACD}$ ở vị trí so le trong => AB//CD

Độ dài quãng đường từ sân vận động Old Trafford đến tháp đồng hồ Big Ben là $200.1,609344=321,8688$ km.

Để kết quả có độ chính xác $0,5$ ta cần làm tròn $321,8688$ đến chữ số thập phân thứ nhất, kết quả là $321,8688\approx 321,9$ km.

(-0,25 )5 : $x$ = (-0,25)3

                $x$ = (-0,25)5 : (-0,25)3

                $x$ = (-0,25)2

                $x$ = 0,0625

0,75 + $\genfrac{}{}{0ex}{}{9}{5}$ ( 1,5 - $\genfrac{}{}{0ex}{}{2}{3}$ )2

= 0,75 + $\genfrac{}{}{0ex}{}{9}{5}$ ( $\genfrac{}{}{0ex}{}{3}{2}$ - $\genfrac{}{}{0ex}{}{2}{3}$)2

= 0,75 + $\genfrac{}{}{0ex}{}{9}{5}$ ($\genfrac{}{}{0ex}{}{5}{6}$)2

= 0,75 + $\genfrac{}{}{0ex}{}{5}{4}$

= 0,75 + 1,25

= 2 

$\genfrac{}{}{0ex}{}{-22}{25}$ + ( $\genfrac{}{}{0ex}{}{22}{7}$ - 0,12)

= $\genfrac{}{}{0ex}{}{-22}{25}$ + ( $\genfrac{}{}{0ex}{}{22}{7}$ - $\genfrac{}{}{0ex}{}{3}{25}$)

= $\genfrac{}{}{0ex}{}{-22}{25}$ + $\genfrac{}{}{0ex}{}{22}{7}$ - $\genfrac{}{}{0ex}{}{3}{25}$

= - ( $\genfrac{}{}{0ex}{}{22}{25}$ + $\genfrac{}{}{0ex}{}{3}{25}$) + $\genfrac{}{}{0ex}{}{22}{7}$

= -1 + $\genfrac{}{}{0ex}{}{22}{7}$

= $\genfrac{}{}{0ex}{}{-7}{7}$ + $\genfrac{}{}{0ex}{}{22}{7}$

= $\genfrac{}{}{0ex}{}{15}{7}$
 

3

In Ha Noi, the number of death by traffic accident is considered as large as the number of death by plague. There's about more than 30 people die everyday.

With the traffic conditions in Ha Noi, accident is object to happen. The roads are too narrow to travel easily. Moreover, many pot-holes can appear everywhere to threaten the goers. On the roads, there're sometimes the illogical roundabouts. They are not only useless, but also make the traffic more chaotic. To solve this problem, we only have one way, it's improving the road. However, it is impossible for the government to widen the roads because of limited land. Whenever theroads are repaired, the traffic is more dangerous with the unfinished structures. People still travel on the repairing roads, and the roads are more and more narrow. We also can build the tunnels but it is very costly. Viet Nam has to borrow money from other countries and no one knows when the government can pay it back. As you know, Ha Noi is a monsoonal tropical country, it has a lot of rain every year. During the rainy season, the roads are flooded because all the waste pipes are stuck by rubbish and become very dirty.

1 I have many hobbies, but I reading most. Books are always a good friend to me. It is a good way to improve my vocabularies by exposing many new words.I star to reading book when i in grade 3.my brother inspired me to do that.I usualy share my hobby with my friend and my english teacher.By reading, I get better at concentration because it requires me to focus on what I am reading for long periods. It also opens up the knowledge door for me. Reading books tell me about the world's history, let me see the structure of the brain, or bring me a story of Sherlock Holmes. I think reading is one of the most interesting indoors activity and I will keep this hobby forever.

2 Nowadays , keeping healthy very important . With the high living standard , our health is worse . So that , we have to have a way to improve our health . With me , to keep healthy , the first thing is doing exerise , it helps me more comfortable , help me stay in shape and make my body more thin . Not only doing exercise , we also have to eat full , we should eat more fruit, fish and eat less meat . Because if we eat too much meat , we will be fat and won't be good for our health .

3 In addition, the tense of Ha Noi people is poor. The roads in the cities are choked with so many vehicles such as motorbikes, bicycles, taxies, buses, cyclos and pedestrians because people do not follow the laws well. They even don't obey the traffic lights or signs. Children are taught about traffic laws while adults are breaking it. Now, the government gives many new strict laws to improve the present posture. Polices are more active than they used to. Everyone travel on

motorbike wears helmet naturally without any enforcement. The traffic is better and better day by day.

In conclusion, with many measures now, the traffic in Ha Noi will be good one day. The poor conditions Ha Noi can solve this problem by the development of economic.

1 Reuse means using something again instead of throwing it away

2 Did your school organise a donation drive last winter?

1 My mother likes going jogging fond in the morning.

2 It’s difficult for my sister finds to lift weights .

3 We collected plastic bottles and we sent them to the factory