Cho(O) đường kính BD; vẽ dây BA: góc DBA = 60 độ. Vẽ dây BC vuông góc BA

a) Tính số đo góc BDC

b) C/m ABCD là hinhf nhữ nhật

c) Vẽ CM vuông góc BD tại I. C/m DM=AB

Cho (O) lấy điểm A. Vẽ các dây AB và AC sao cho góc BAC=60  và O nằm trong góc BAC. Tính số đo cung BC

Cho tam giác đều ABC nội tiếp (O;6cm)/ Cho CO cắt AB tại H

a) Tính diện tích ABC

b) Tính số đo cung BC

1/Cho (O) đường kính CD. Lấy K thuộc bán kính OC; vẽ dây AB vuông góc OC tại K. Tiếp tuyến B cắt OC tại M. C/m tam giác MBC đồng dạng tam giác MDB
2/ Giải phương trình \(\sqrt{\left(x-1\right)^2-\left(x^2-3\right)}=3\)

cho tam giac ABC vuông tại A có AB=9,AC= 12 nội tiếp (O). Vẽ dây AD vuông BC tại H.

a) Tính BH và AD

b) Tính góc BAH

Napoleon III of France was (0).A……. for the invention of the butter substitute known as margarine. He was looking for a cheap (1) ……… to butter for the poorer people of society, and for his army and navy. So he (2) ............... up a prize competition to see who would (3) ............... up with the best solution.

There was only one (4) ................. into this competition, from a man called Meges Mouries. He had (5) ................ over two years experimenting, and finally found an acceptable butter substitute made from milk and various animal fats. It tasted quite pleasant, and spread well on bread, but it was (6) ............. white. (7) ………its colour, Meges¬ Mouries’ invention was awarded the prize. Yellow colouring was added to it at a (8) ............. date.

Margarine soon went into mass (9) ............... and was exported all over the world. In Britain it was called 'Butterine', until protests from farmers (10) ............. to that name being made illegal. Farmers in America were not happy (11) ………....the new arrival on the market either. They (12) …….....to the yellow colouring, saying that it made it resemble butter so (13)……….. that it could deceive consumers.

In effect, Napoleon III's competition is still going on. The ultimate (14) ........... of every margarine manufacturer is to produce a product that is (15) ………… to distinguish from butter. And they keep trying.

0. A responsible B original C fundamental D vital
1. A option B replacement C alternative D choice
2. A set B took C gave D put
3. A make B bring C go D come
4. A competitor B player C attempt D entry
5. A used B spent C tried D made
6. A clear B pure C true D perfect
7. A Despite B Although C However D Nevertheless
8. A further B longer C later D farther
9. A production B creation C industry D construction
10. A changed B ended C brought D led
11. A over B about C at D for
12. A protested B objected C disagreed D argued
13. A justly B nearly C rightly D closely
14. A end B score C goal D finish
15. A impractical B unable C impossible D incapable

Cho (O) đường kính BC= 10. Vẽ BA=6.  Trên tia đối tia AB lấy D: AB=AD

a) Tính AC 

b) Tính góc ADB

c) C/m OB=CD

Cho (O) bán kính OA=R. Gọi I là trung điểm OA, vẽ dây CD vuông góc OA tại I

a) Tính CD theo K

b) Tính góc AOC

b) Tính số đo cung CD