已知函数F(x)=|cos2x+2sinxcosx-sin2x+Ax+B|(1)若F(x)是周期函数,求A,B(2)若F(x)在0≤x≤3π

2025-02-23 18:31:18
推荐回答(1个)
回答1:

F(x)=|cos2x+sin2x+Ax+B|=|
2
sin(2x+
π
4
)+Ax+B|,
(1)若F(x)是周期函数,F(x+π)=F(x),即|
2
sin(2x+
π
4
)+Ax+B|=|
2
sin(2π+2x+
π
4
)+Ax+Aπ+B|,
可得A=0,B为任意实数;
(2)∵0≤x≤
2
,∴
π
4
≤2x+
π
4
13π
4

∴-1≤
2
sin(2x+
π
4
)≤
2

当A=0,B=-
2
时,
2
+1≥F(x)=|
2
sin(2x+