函数f(x)=asin(x+π6)+3sin(x-π3)是偶函数,则a=______.-数学

题目简介

函数f(x)=asin(x+π6)+3sin(x-π3)是偶函数,则a=______.-数学

题目详情

函数f(x)=asin(x+
π
6
)+
3
sin(x-
π
3
)
是偶函数,则a=______.
题型:填空题难度:中档来源:不详

答案

∵f(x)=asin(x+class="stub"π
6
)+
3
sin(x-class="stub"π
3

=a(
3
2
sinx+class="stub"1
2
cosx)+
3
class="stub"1
2
sinx-
3
2
cosx)
=
3
2
(a+1)sinx+(class="stub"a
2
-class="stub"3
2
)cosx为偶函数,
∴f(-x)=f(x),
∴a+1=0,
∴a=-1.
故答案为:-1.

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