设函数f(x)=sin(πx/4-π/6)-2cos²πx/8+1
问题描述:
设函数f(x)=sin(πx/4-π/6)-2cos²πx/8+1
答
f(x)=sin(πx/4-π/6)-2cos²πx/8+1=sin(πx/4-π/6)-(2cos²πx/8-1)=sinπx/4cosπ/6-cosπx/4sinπ/6-cosπx/4=√3/2*sinπx/4-3/2cosπx/4=√3(1/2sinπx/4-√3/2*cosπx/4)=√3sin(πx/4-π/3)T=2π...O(∩_∩)O哈哈~,第一问我对了,可是第二问那个对称应该怎么求?有点搞不清楚。g(x)与f(x)关于直线x=1对称g(x)=f(2-x)=√3sin[π(2-x)/4-π/3)=√3sin(-πx/4+π/6)=-√3sin(πx/4-π/6)∵0≤x≤4/3∴0≤ πx/4≤π/3∴-π/6≤πx/4-π/6≤π/6∴-1/2≤sin(πx/4-π/6)≤1/2∴-√3/2≤-√3sin(πx/4-π/6)≤√3/2∴πx/4-π/6=-π/6,x=0时,g(x)取得最大值√3/2