行列式
（1）求A； （2）将函数y=f（x）的图象向左平移
|
（1）由题意，M11=
=Asinxcosx=. Asinx 0 1 cosx .
sin2x，M21=-A 2
=-Acos2x+. Acosx A 2 1 cosx .
=-A 2
cos2x…（2分）A 2
∴f(x)=
sin2x-A 2
cos2x=A 2
sin(2x-
A2 2
)…（3分）π 4
∴fmax=
=4，∴A=4
A2 2
…（1分）2
（2）向左移
得y=4sin(2x-π 12
)，…（2分）π 12
横坐标变为原来2倍得g(x)=4sin(x-
)…（1分）π 12
∵x∈(-
，π 12
)，∴x-11π 12
∈(-π 12
，π 6
)…（1分）5π 6
∴g(x)=4sin(x-
)∈(-2，4]…（3分）π 12
| 阅读理解。 |
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| 1. Some people say the world is smaller than before because _____________ . |
[ ] |
| A. all people kike to search the Internet. B. the Internet makes the earth smaller in size C. the Internet brings the outside world closer to them |
| 2. The sentence "The Internet also helps us open our mind." means _______ . |
[ ] |
| A. the Internet is new to us B. something is wrong with our minds C. we can learn more with the help of the Internet |
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[ ] |
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[ ] |
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[ ] |
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