Cho nửa đường tròn (O;R) đường kính AB.Kẻ hai tiếp tuyến Ax,By với nửa đường tròn , Điểm M thuộc nửa đường tròn(M khác A và B) tiếp tuyến tại M của nửa đường tròn cắt Ax,By lần lượt tại C và D .Gọi E là giao điểm của MA và OC; F là giao điểm của MB và OD

a,CMR: tam giác COD vuông tại C

b,Khi M chuyển động trên nửa đường tròn . CMR: AC.BD không đổi

c,Cho BD =R\(\sqrt{3}\) tính MA theo R

d,Kẻ MH vuông góc với AB tại H. CMR: MH,BC,EF đồng quy

Cho a,b,c > 0thoar mãn a+b+c=1. Tìm GTNN của biểu thức:\(P=\dfrac{9}{2\left(ab+bc+ca\right)}+\dfrac{2}{a^2+b^2+c^2}\)

Mark the letter A,B,C or D to indicate the underlined part that needs correction in each of the following questions

1.Those who come from Baffin Island often live in an igloo:a house building from blocks of ice.

2.I am going for a diet next week and hope to lose ten pounds before Christmas

3.I wish I have his mobile phone number so that we could tell him the good news

4.The children had to go barefootedly because there was no money for shoes

5.Today's children no longer engage with the nature wold

6.Despite giving a second chance,she couldn't manage to pass the exam

7. A magical way is going to prepare by the inhabitants to solve this curse

8.Alan didn't use to liked children,but it's different now he has hia own

9.Alex said he will ask his grandparents about their old days

10.I'm hopeless at foreign languges,but I wish I speak Spanish and French

Complete the second sentence so that it has the same meaning as the first sentence

1.They often went to school by bike when thay were young

=>They used

2.She has taught her children to play piano for 4 years

=>She started

3.It's a pity I can't cook as well as my mom

=>I wish

4.He doesn't have meals with his family any more

=>He used

5.It took me a long time to be accustomed to living in the country

=>It took me a long time to get

6.My school is near my home,so I go to school on foot every day

=>My school isn't

7.I would like my sister to improve her English speaking

=>I wish

8.Vietnamese people only eat dried candied fruit at Tet

=>Dried candied fruit

I.Write sentences,using the clues given

1.he/used/play/football/local team,/but/he/too/old/now

2.Beth/wish/she/can/stay/Cambridge/forever

3.American family life/change/greatly/the last three decades.

4. she/travel/over/the world/if/she/be/rich

5.they/urge/the parliament/approve/plans/their reform program

6. how/you/get/know/this university?

7. I/suppose/we/can/pay/credit card/but/we/had better/chech/first.

8. women/stay/home/preparing food/making clothes/the past.

Cho hàm số y = (2m - 4)x + 2 (1) (m là tham số)

a) Tìm m để hàm số (1) là hàm số bậc nhất đồng biến trên R

b) Tìm m để đường thẳng (1) cắt đường thẳng y = x + 1 tại điểm có hoành độ bằng 2

c) Xác định m sao cho khoảng cách từ gốc tọa độ đến đồ thị hàm số đã cho bằng 1

Câu hỏ