设函数f(x)=2mcos2x-2
（1）求m，n的值； （2）若f（x）=2，求x的值． |
（1）f(x)=m(1+cos2x)-
msin2x+n3
=2mcos(2x+
)+m+n．π 3
∵x∈[0，
]，π 2
∴2x+
∈[π 3
，π 3
]4π 3
cos(2x+
)∈[-1，π 3
]，1 2
∵m＞0，2mcos(2x+
)∈[-2m，m]，π 3
所以f（x）max=2m+n=4，
f（x）min=-m+n=1，
m=1，n=2
（2）由（1）可知，m＞0时，
f(x)=2cos(2x+
)+3=2所以cos(2x+π 3
)=-π 3
，结合定义域为[0，1 2
]，π 2
解得x=
．π 6
阅读下面对话，从方框内 7 个选项中选择 5 个恰当的句子完成此对话，并将其番号填入题前括号 内。
B. Oh, it’s wonderful. It’s one of the most interesting places I have ever seen. A.小题2: B. I went to many places, but I’m interested in Disneyland most. A. Could you tell me something about it? B. Well, it has lots of cartoon characters there, like Mickey Mouse, Donald Duck and so on. A. 小题3:Tell me more about it. B. 小题4:Such as the roller coaster. A.小题5: B. I went there by plane. |