d. Ta có : \(\left\{{}\begin{matrix}BA=BM\left(\Delta DBA=\Delta DBM\right)\\DA=DM\left(\Delta DBA=\Delta DBM\right)\end{matrix}\right.\)

\(\Rightarrow\) BD là đường trung trực của đoạn thẳng AM

\(\Rightarrow BD\perp AM\)

Vì \(\left\{{}\begin{matrix}\text{BD\perp AM}\left(cmt\right)\\BD\perp CH\left(gt\right)\end{matrix}\right.\)

\(\Rightarrow\) AM // CH

Mà AM // EC

\(\Rightarrow\) Tia CH và tia EC trùng nhau

\(\Rightarrow\) 3 điểm C , H , E thẳng hàng

c) Xét \(\Delta CDM\) và \(\Delta EDA\) , ta có :

\(\left\{{}\begin{matrix}\widehat{DMC}=\widehat{DAE}=90^o\\DM=DA\left(\Delta DBA=\Delta DBM\right)\\\widehat{CDM}=\widehat{EDA}\text{( đối đỉnh )}\end{matrix}\right.\)

\(\Rightarrow\Delta CDM=\Delta EDA\left(g.c.g\right)\)

Ta có : \(\left\{{}\begin{matrix}BA=BM\left(\Delta DBA=\Delta DBM\right)\\MC=AE\left(\Delta CDM=\Delta EDA\right)\\BM+MC=BC\left(M\in BC\right)\\BA+AE=BE\left(A\in BE\right)\end{matrix}\right.\)

\(\Rightarrow BC=BE\)

\(\Rightarrow\Delta BEC\) cân tại B

\(\Rightarrow\widehat{MCE}=\dfrac{180^o-\widehat{ABM}}{2}\left(1\right)\)

Ta có : \(\Delta ABM\) cân tại B ( cmt )

\(\Rightarrow\widehat{BMA}=\dfrac{180^o-\widehat{ABM}}{2}\left(2\right)\)

Từ ( 1 ) và ( 2 )

\(\Rightarrow\widehat{MCE}=\widehat{BMA}\)

Mà \(\widehat{MCE}\) và ở vị trí đồng vị

\(\Rightarrow\) AM // EC

Ta có : \(DC=DE\left(\Delta CDM=\Delta EDA\right)\)

\(\Rightarrow\Delta DCE\) cân tại D

Xét \(\Delta AMB\) và \(\Delta EMC\) , ta có :

\(\left\{{}\begin{matrix}MA=ME\left(gt\right)\\\widehat{AMB}=\widehat{EMC}\text{ ( đối đỉnh )}\\MB=MC\text{ ( AM là trung tuyến của \Delta ABC )}\end{matrix}\right.\)

\(\Rightarrow\Delta AMB=EMC\left(c.g.c\right)\)

\(\Rightarrow AB=EC\) ( 2 cạnh tương ứng )

b. Ta có : \(\left\{{}\begin{matrix}AB< AC\left(gt\right)\\AB=EC\left(cmt\right)\end{matrix}\right.\)

\(\Rightarrow EC< AC\)

c. Ta có : \(EC< AC\left(cmt\right)\)

\(\Rightarrow\widehat{CAM}< \widehat{AEC}\) ( quan hệ giữa cạnh và góc đối diện trong 1 tam giác )

Mà \(\widehat{BAM}=\widehat{AEC}\left(\Delta AMB=\Delta EMC\right)\)

\(\Rightarrow\widehat{CAM}< \widehat{BAM}\)

Chất X là trieste của glixerol với axit béo không no, 1 mol X phản ứng tối đa với 4 mol H₂ (Ni, t^o). Đốt cháy hoàn toàn với a mol X trong khí O₂ dư, thu được b mol H₂O và V lít khí CO₂ (đktc). Biểu thức liên hệ giữa các giá trị của a, b và V là 

A. V = 22,4(3a + b).

B. V = 22,4(7a + b). 

C. V = 22,4(6a + b). 

D. V = 22,4(4a + b). 

II. Revision 2

1. Choose the best answer A,B or C.

1. I saw a lot of beautiful fish at Tri Nguyen Aquarium yesterday.

2. He goes to the dentist beacause he has a toothache.

3.Mrs. Oanh is happy and her children are, too

4. You shouldn't play video games for a long time.

2. Use the correct form of the verbs in the brackets.

1. Last night we (go) to the cinema.

=> Last night we went to the cinema.

2. Hoa (brush) her teeth twice a day.

=> Hoa brushes her teeth twice a day.

3. I'd like (go) fishing.

=> I'd like to go fishing.

4. You (do) your homework yesterday?

=> Did you do your homework yesterday ?

3. Rewrite, beginning as shown, so that the meaning stay that same.

1. Shall we go to the movie?

Let's go to the movie.

2.Ba is a quick swimmer.

Ba swims quickly.

3. I don't like pork. They don't like pork

I don't like pork, and they don't like, either.

4. Lan has a toothache.

She should go to the dentist.

4. Rearrange the following words to complete sentences.

1. slowly / he / very / runs.

=> He runs very slowly.

2. sports / Ba / taking / in / part / prefers.

=> Ba prefers taking part in sports.

3. at / let's / 7:00 / home / go.

=> Let's go home at 7:00

4. was / you / what / with / wrong ?

=> What was wrong with you ?

5. Fill in the blank with the words given. felt - weighed - checked - took - medical

Yesterday, ba had a (1) medical check - up. The doctor (2) weighed him. Then she measured his height. After that, she (3) took his temperature. Then she (4) checked his eyes and ears. Everything was normal. Finally, Ba left. He left very happy.

Do you think the ___ price will increase next month?

a. gases

b.fossil fuel

c. fuel

d. natural gases

2. people won't use flying cars ___ the year 2050

A. after

B. before

C. during

D. until

15. Which ___ of transport do you think will be used in the future?

a. mean

B. means

C. meanings

D. meaning

16. A jet pack doesn't ___ a lot of space.

A. occur

B. bring

C. take

D, have

17.The city is facing serious __ problems

a. pollution

b polluted

c, polute

d, polutant

18

We will use more ___ energy in the future

A. sun

B. sunny

C. solar

D. sunlight

19. We are looking for types of vehicles that help us to avoid___

a, walking

B. traffic jams

C. rush hours

D. traffic

20. We believe that urban transport pods can travel ___ around 30kph

A. in

B. at

C. with

D. on

1. Did you see (see) the film on television last night?

2. Our class starts ( start) at 7.15 and finishes( finish) at 11.45 every morning

3. She gets fat because she is always tasting things while she is cooking ( cook)

4. Bill decided to buy ( buy) a new car rather than a used one

5. Long felled ( fall) down the stairs this morning and broke ( break) his leg

6. George is interested in taking( take) an art class

7. The package has to be ( be) there tomorrow. Will it be( be) there in time?

- Don’t worry. I am going to send it by express mail.

- Xuất hiện phổi, hô hấp nhờ sự nâng hạ của thềm miệng.

- Da có nhiều mạch máu làm nhiệm vụ hô hấp.

1. Cars of the futer will do less damage to the environment and will be equipped with better safety devices to limit the number of accidents and deaths.

2. Energies could be powered by a rubbish - fuelled reactor to make use of all the waste we produce.

3. Petrol may be replaced by fuel caells which separate hydrogen from oxygen in water.

4. Cars will have sensors to detect pedestrians and other cars will have air cushions.

5. Vehicles can ' take ' to each other to regulate flow , it means the end of traffic jams.

6. Cars powered by fuels cells are already being developed.

7. We will see this type of cars on the roads in twenty years.

8. Environment and safety improvements will be popular soon.