函数y=cos(x+5°)+3√2 cos(x+50°)的值域是?
问题描述：
函数y=cos(x+5°)+3√2 cos(x+50°)的值域是?
答
y=cos(x+5°)+3√2 cos(x+50°)=cos(x+5°)+3√2 cos(x+5°+45°)=cos(x+5°)+3√2 [cos(x+5°)cos45°-sin(x+5°)sin45°]=cos(x+5°)+3 [cos(x+5°)-sin(x+5°)]=4cos(x+5°)-3sin(x+5°)=5[4/5*cos(x+5°)-3/5*si...