问题
选择题
已知sin(α-π)=
|
答案
∵sin(α-π)=
，且α∈(-2 3
，0)，π 2
∴sinα=-
，cosα=2 3
=1-sin2α
，5 3
∴tanα=
=-sinα cosα
，2 5 5
故选 B．
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已知sin(α-π)=
|
∵sin(α-π)=
，且α∈(-2 3
，0)，π 2
∴sinα=-
，cosα=2 3
=1-sin2α
，5 3
∴tanα=
=-sinα cosα
，2 5 5
故选 B．
| 阅读理解。 | ||||||||||
| The 30th Olympic host (主办) city, London, is opening its arms to the world. It's the capital city of the UK and one of the business centers in the world. It has a history of more about 2000 years. Many places of London were once villages. Today, London is a growing city with about 7 million people. They came from all parts of the world. Their ways of life are not the same but harmonious (和谐的). Their favorite food is pie and mashed potato. The symbol of London is a red double-deck (双层) bus. It came to London in 1956 and was in use there until 2005. Now it only runs on two main streets in the center of London. Let's look forward to London's wonderful show next year! | ||||||||||
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