已知函数f(x)=sin²ωx+√3cosωxcos(π/2-ωX)ω>0 且函数y=f(x)的图像相邻两条对称轴之间的距离为π/2 1.求f(π/6)的值 2.若函数f(kπ+π/12)(K>0)在区间【-π/6,π/3】上单调
问题描述:
已知函数f(x)=sin²ωx+√3cosωxcos(π/2-ωX)ω>0 且函数y=f(x)的图像相邻两条对称轴之间的距离为π/2 1.求f(π/6)的值 2.若函数f(kπ+π/12)(K>0)在区间【-π/6,π/3】上单调递减,求k的取值范围
答
cos2ωx = 1-2 sin²ωxf(x)=sin²ωx+√3cosωxcos(π/2-ωX) = (1-cos2ωx)/2 +√3cosωxsinωx=1- (1/2)cos2ωx + (√3/2)sin2ωx=1 + sin2ωx *(√3/2) - cos2ωx * (1/2)=1 +sin(2ωx-π/6) ...是这个式子:√3cosωxcos(π/2-ωX)前面不变,后面的cos(π/2-ωX)即cos(90度减一个角)=sin(那个被减的角)