giúp mình câu b ạ, cả câu c thì càng tốt

Mấy câu tính toán trình bày ngắn gọn giúp mình ạ

H=1; N=14; C=12; O=16; Na=23; Mg=24; Al=27; P = 31; S=32; Cl=35,5; K=39; Ca=40;

Fe = 56; Cu = 64; Zn = 65; Br =80; Ag = 108, Ba=137

Cho tam giác ABC vuông ở A có AB = 12 cm, AC = 16cm. Kẻ đường thẳng vuông góc với BC tại B cắt cạnh AC kéo dài tại E.
a) Tính AE, góc C.
b) Kẻ AM vuông góc với BC tại M. Chứng minh : MAB
đồng dạng với  ABE
c) Gọi CF là tia phân giác của góc BCE (F BE). Kẻ BH
vuông góc với CF tại H. Chứng minh : góc CEF = góc
CHA
d) Tính diện tích tứ giác EFMC

GIÚP MÌNH CÂU D Ạ!!!

Cho tam giác ABC vuông ở A có AB = 12 cm, AC = 16cm. Kẻ đường thẳng vuông góc với BC tại B cắt cạnh AC kéo dài tại E.
a) Tính AE, góc C.
b) Kẻ AM vuông góc với BC tại M. Chứng minh : MAB
đồng dạng với  ABE
c) Gọi CF là tia phân giác của góc BCE (F BE). Kẻ BH
vuông góc với CF tại H. Chứng minh : góc CEF = góc
CHA
d) Tính diện tích tứ giác EFMC

Giải giúp mình câu C ạ

Gợi í là cm tam giác CAH đồng dạng với tam giác CFE theo cgc

Cho tam giác ABC vuông ở A có AB = 12 cm, AC = 16cm. Kẻ đường thẳng vuông góc với BC tại B cắt cạnh AC kéo dài tại E.
c) Gọi CF là tia phân giác của góc BCE (F BE). Kẻ BH
vuông góc với CF tại H. Chứng minh : góc CEF = góc
CHA
d) Tính diện tích tứ giác EFMC

: Cho tam giác ABC vuông ở A có AB = 12 cm, AC = 16cm. Kẻ đường thẳng vuông góc với BC tại B cắt cạnh AC kéo dài tại E.
a) Tính AE, góc C.
b) Kẻ AM vuông góc với BC tại M. Chứng minh : MAB
đồng dạng với  ABE
c) Gọi CF là tia phân giác của góc BCE (F BE). Kẻ BH
vuông góc với CF tại H. Chứng minh : góc CEF = góc
CHA
d) Tính diện tích tứ giác EFMC

CÂU C VÀ D LÀ ĐƯỢC Ạ!

Exercise 2:     Choose the best answer.

1. Had you told me that this was going to happen, I _______ it.

A. would never have believedB. don’t believe C. hadn’t believedD. can’t believe

2. Put all the toys away……….. someone slips and falls on them.

A. provided that B. unless C. in case     D. so long as

3. Many argue that the world will never make the switch to cleaner forms of energy………… easily obtainable soil sources remain.

A. suppose that           B. providing that         C. unless                  D.as long as

4. ……….you to be offered that job, would you have to move to another city?

A. should B.  Were C. had D. Provided that

5. You will find their house ____ you take a good street map with you.

A. as long as B. even if                          C. if only D. otherwise:

6. You’d better stop spending money, ___ you will end up in debt.

A. unless B. otherwise                          C. if   D. in case

7. Henry__________ a rich man today if he had been more careful in the past.

     A. will have been B. will be              C. would have been                          D. would be

8._________ you visit him, give him my best wishes.

A. Could   B. Would   C. Should  D. Might

9. Were she ten years younger, she ______________ the beauty contest.

A. will enter              B. had entered                 C. would enter D. would have entered

10. If it………..their encouragement, he could have given it up.

A. had been for          B. hadn’t been              C. hadn’t been for     D. wouldn’t have been for

11. ____ any employee be ill, they must call the office to inform their head of departure. 

A. Were B. Should C. Had D. If

12. If Lucy’s car ____ down, she would be here right now.

A. didn’t break B. hadn’t broken C. wouldn’t have been D. doesn’t break

13. Harry would certainly have attended the proceedings _________ .

A. if he didn’t get a flat tyre B. had he not had a flat tyre C. had the tyre not flattened itself D. if the flat tyre didn’t happen

14.        If I _____ my wallet at home this morning, I _____ money for lunch now.

A. leave / will have     B. didn’t leave / would have C. hadn’t left / would have D. hadn’t left / would have had

15.        I………you sooner had someone told me you were in the hospital. 

A-would have visited B-visited C-had visited   D-visit

16.        ………then what I know today,I would have saved myself a lot of time and trouble over the years.

     A-had I known       B-did I know      C-If I know                  D- If I would know

17.        If someone ……in to the store,smile and say, “May I help you?”

A-comes  B-came  C-would come   D-could come

18.  Trees won’t grow ……….. there is enough water.

A. if                    B. when            C. unless         D. as

Exercise 3 choose the best answer

1. But for two minor mistakes, I would have got full marks for the test.

A. If  I didn’t make two minor mistakes, I would have got full marks for the test.

B. I would have got full marks for the test if there hadn’t been these two minor mistakes

C. Had I made two minor mistakes, I would have got full marks for the test.

D. If the mistakes hadn’t been minor, I could have got full marks for the test.

2. Get in touch with me as soon as possible if you change your mind about the trip.

A. Should you change your mind about the trip, contact me as soon as possible

B. If you changed your mind about the trip, get in touch with me as soon as possible.

C. You should call me whenever you changed your mind about the trip.

D. Having changed your mind about the trip, you should get in touch with me soon

3. If it hadn’t been for the goalkeeper, United would have lost.

A. United didn’t lose the game thanks to their goalkeeper.         B. United lost the match because of their goalkeeper.

C. Without their goalkeeper, United could have wonD. If their goalkeeper didn’t play so well, United would have lost.

4. Without his help, we would all die.

A. We died because he didn’t help us.

B. He didn’t help us, so we died.

C.   If it hadn’t been for his help, we would all have died    

D. If he had helped us, we wouldn’t have died.

5. Had the announcement been made earlier, more people would have attended the lecture.

A. Not many people came to hear the lecture because it was held too late,

B. The lecture was held earlier so that more people would attend

C. Fewer people attended the lecture because of the early announcement.

D. Since the announcement was not made earlier, fewer people came to hear the lecture.

6. But for Helen acting so wonderfully, the play would be a flop

A. Helen acted so wonderfully, but the play was a flop.    

B. If it wasn’t for Helen’s wonderful acting, the play would be a flop

C. The play was a flop although Helen acted so wonderfully.

D. The play was a flop although Helen was such a wonderful actor.

7. Provided your handwriting is legible, the examiner will accept your answer.

A. Although the examiner cannot read your handwriting, he will accept your answer,

B. Whatever your handwriting, the examiner will accept your answer.

C. The examiner will accept your answer if your handwriting is beautiful

D. So long as the examiner can read your handwriting, he will accept your answer.

8. But for his father’s early retirement, Richard would not have taken over the family business.

A. Richard only took over the family business because his father decided to retire early.

B. Richard didn’t take over the family business because his father didn’t retire early

C. His father retired early but he still ran the family business

D. Richard’s father didn’t want him to take over the family business despite his retirement

9. Were it not for the money, the job wouldn’t be worthwhile

A. This job is not rewarding at all                                       

B. This job offers a poor salary

C. Although the salary is poor, the job is worthwhile 

D. The only thing that makes this job worthwhile is the money.

10. You can stay in the flat for free if you pay the bills.

A. Provided you pay the bills, you can stay in the flat for free.

B. Without the bills paid, you can stay in the free flat.

C. Unless the flat is free of bills, you cannot stay in it.

D. Whether you pay the bills or stay in the flat, it is free.

11:  She is now leading a normal life as a result of all the support she received from social workers.

A. Had it not been for the social workers, she wouldn’t be leading such a normal life now.

B.Because she receives all the support from social workers, she is leading a normal life now

C. If she didn’t receive all the support from social workers, she wouldn’t be leading a normal life now.

D. Had she not received so much support from social workers, she wouldn’t be leading such a normal life now.

12.In my experiments, the liquid is cooled to 32_­­­ºF. It always freezes.

A. If you cool the liquid to 32 degrees, it froze.

B. If you cooled the liquid to 32 degrees, it would freeze.

C. If you cool the liquid to 32 degrees, it will freeze.

D. If you had cooled the liquid to 32 degrees, it would have frozen.

1. Had you told me that this was going to happen, I _______ it.

   A. would never have believed   B. don’t believe C. hadn’t believedD. can’t believe

2. Put all the toys away……….. someone slips and falls on them. A. provided that B. unless C. in case         D. so long as

3. Many argue that the world will never make the switch to cleaner forms of energy………… easily obtainable soil sources remain.A. suppose that                B. providing that         C. unless             D.as long as

4. ……….you to be offered that job, would you have to move to another city? A. should B.  Were C. had D. Provided that

5. You will find their house ____ you take a good street map with you. A. as long as B. even if    C. if only D. otherwise:

6. You’d better stop spending money, ___ you will end up in debt. A. unless B. otherwise        C. if   D. in case

7. Henry__________ a rich man today if he had been more careful in the past.

     A. will have been B. will be              C. would have been                          D. would be

8._________ you visit him, give him my best wishes. A. Could   B. Would   C. Should  D. Might

9. Were she ten years younger, she ______________ the beauty contest.

A. will enter              B. had entered                 C. would enter        D. would have entered

10. If it………..their encouragement, he could have given it up.

A. had been for          B. hadn’t been              C. hadn’t been for     D. wouldn’t have been for

11. ____ any employee be ill, they must call the office to inform their head of departure.  A. Were B. Should C. Had D. If

12. If Lucy’s car ____ down, she would be here right now. A. didn’t break B. hadn’t broken C. wouldn’t have been D. doesn’t break

13. Harry would certainly have attended the proceedings _________ .

A. if he didn’t get a flat tyre B. had he not had a flat tyre C. had the tyre not flattened itself D. if the flat tyre didn’t happen

14.        If I _____ my wallet at home this morning, I _____ money for lunch now.

A. leave / will have     B. didn’t leave / would have C. hadn’t left / would have D. hadn’t left / would have had

15.        I………you sooner had someone told me you were in the hospital.  A-would have visited B-visited C-had visited   D-visit

16.        ………then what I know today,I would have saved myself a lot of time and trouble over the years.

     A-had I known             B-did I know  C-If I know                D- If I would know

17.        If someone ……in to the store,smile and say, “May I help you?” A-comes  B-came C-would come   D-could come

18.  Trees won’t grow ……….. there is enough water.A. if           B. when            C. unless         D. as

Exercise 3 choose the best answer

1. But for two minor mistakes, I would have got full marks for the test.

A. If  I didn’t make two minor mistakes, I would have got full marks for the test.

B. I would have got full marks for the test if there hadn’t been these two minor mistakes

C. Had I made two minor mistakes, I would have got full marks for the test.

D. If the mistakes hadn’t been minor, I could have got full marks for the test.

2. Get in touch with me as soon as possible if you change your mind about the trip.

A. Should you change your mind about the trip, contact me as soon as possible

B. If you changed your mind about the trip, get in touch with me as soon as possible.

C. You should call me whenever you changed your mind about the trip.

D. Having changed your mind about the trip, you should get in touch with me soon

3. If it hadn’t been for the goalkeeper, United would have lost.

A. United didn’t lose the game thanks to their goalkeeper.         B. United lost the match because of their goalkeeper.

C. Without their goalkeeper, United could have wonD. If their goalkeeper didn’t play so well, United would have lost.

4. Without his help, we would all die.

A. We died because he didn’t help us.                                                             B. He didn’t help us, so we died.

C.   If it hadn’t been for his help, we would all have died                 D. If he had helped us, we wouldn’t have died.

5. Had the announcement been made earlier, more people would have attended the lecture.

A. Not many people came to hear the lecture because it was held too late,

B. The lecture was held earlier so that more people would attend

C. Fewer people attended the lecture because of the early announcement.

D. Since the announcement was not made earlier, fewer people came to hear the lecture.

6. But for Helen acting so wonderfully, the play would be a flop

A. Helen acted so wonderfully, but the play was a flop.     B. If it wasn’t for Helen’s wonderful acting, the play would be a flop

C. The play was a flop although Helen acted so wonderfully. D. The play was a flop although Helen was such a wonderful actor.

7. Provided your handwriting is legible, the examiner will accept your answer.

A. Although the examiner cannot read your handwriting, he will accept your answer,

B. Whatever your handwriting, the examiner will accept your answer.

C. The examiner will accept your answer if your handwriting is beautiful

D. So long as the examiner can read your handwriting, he will accept your answer.

8. But for his father’s early retirement, Richard would not have taken over the family business.

A. Richard only took over the family business because his father decided to retire early.

B. Richard didn’t take over the family business because his father didn’t retire early

C. His father retired early but he still ran the family business

D. Richard’s father didn’t want him to take over the family business despite his retirement

9. Were it not for the money, the job wouldn’t be worthwhile

A. This job is not rewarding at all                                        B. This job offers a poor salary

C. Although the salary is poor, the job is worthwhile 

D. The only thing that makes this job worthwhile is the money.

10. You can stay in the flat for free if you pay the bills.

A. Provided you pay the bills, you can stay in the flat for free. B. Without the bills paid, you can stay in the free flat.

C. Unless the flat is free of bills, you cannot stay in it. D. Whether you pay the bills or stay in the flat, it is free.

11:  She is now leading a normal life as a result of all the support she received from social workers.

A. Had it not been for the social workers, she wouldn’t be leading such a normal life now.

B.Because she receives all the support from social workers, she is leading a normal life now

C. If she didn’t receive all the support from social workers, she wouldn’t be leading a normal life now.

D. Had she not received so much support from social workers, she wouldn’t be leading such a normal life now.

12.In my experiments, the liquid is cooled to 32_­­­ºF. It always freezes.

A.  If you cool the liquid to 32 degrees, it froze.

B.  If you cooled the liquid to 32 degrees, it would freeze.

C.  If you cool the liquid to 32 degrees, it will freeze.

D.  If you had cooled the liquid to 32 degrees, it would have frozen.

Câu C ạ